diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index a6ebe193e..64c25e494 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -3235,8 +3235,7 @@ public:
     AstNodeModule* classOrPackagep() const {
         AstNode* foundp = m_classOrPackageNodep;
         while (auto* const anodep = VN_CAST(foundp, Typedef)) foundp = anodep->subDTypep();
-        while (auto* const anodep = VN_CAST(foundp, ClassRefDType))
-            foundp = anodep->classOrPackagep();
+        if (auto* const anodep = VN_CAST(foundp, ClassRefDType)) foundp = anodep->classp();
         return VN_CAST(foundp, NodeModule);
     }
     AstPackage* packagep() const { return VN_CAST(classOrPackageNodep(), Package); }
diff --git a/src/V3Common.cpp b/src/V3Common.cpp
index ad4ecaf6e..6f983809c 100644
--- a/src/V3Common.cpp
+++ b/src/V3Common.cpp
@@ -86,7 +86,7 @@ static void makeToStringMiddle(AstClass* nodep) {
             }
         }
     }
-    if (nodep->extendsp() && nodep->extendsp()->classp()->user1()) {
+    if (nodep->extendsp()) {
         string stmt = "out += ";
         if (!comma.empty()) stmt += "\", \"+ ";
         // comma = ", ";  // Nothing further so not needed
diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index fc4555304..fb90cf866 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -2379,6 +2379,7 @@ private:
             iterateChildren(nodep);
         }
     }
+    virtual void visit(AstClassOrPackageRef* nodep) override { iterateChildren(nodep); }
     virtual void visit(AstPin* nodep) override { iterateChildren(nodep); }
 
     void replaceLogEq(AstLogEq* nodep) {
diff --git a/src/V3LinkCells.cpp b/src/V3LinkCells.cpp
index ec0da2f09..03703c2c8 100644
--- a/src/V3LinkCells.cpp
+++ b/src/V3LinkCells.cpp
@@ -471,9 +471,6 @@ private:
         }
     }
 
-    // Accelerate the recursion
-    // Must do statements to support Generates, math though...
-    virtual void visit(AstNodeMath*) override {}
     virtual void visit(AstNode* nodep) override { iterateChildren(nodep); }
 
     // METHODS
diff --git a/src/V3LinkDot.cpp b/src/V3LinkDot.cpp
index 45e5a2038..f5dc1b59e 100644
--- a/src/V3LinkDot.cpp
+++ b/src/V3LinkDot.cpp
@@ -1988,6 +1988,16 @@ private:
         }
     }
 
+    bool isParamedClassRef(const AstNode* nodep) {
+        if (const auto* classRefp = VN_CAST(nodep, ClassOrPackageRef)) {
+            if (classRefp->paramsp()) return true;
+            const auto* classp = classRefp->classOrPackageNodep();
+            while (const auto* typedefp = VN_CAST(classp, Typedef)) classp = typedefp->subDTypep();
+            return VN_IS(classp, ClassRefDType) && VN_AS(classp, ClassRefDType)->paramsp();
+        }
+        return false;
+    }
+
     // VISITs
     virtual void visit(AstNetlist* nodep) override {
         // Recurse..., backward as must do packages before using packages
@@ -2172,11 +2182,17 @@ private:
                 // if (!start) { nodep->lhsp()->v3error("Package reference may not be embedded in
                 // dotted reference"); m_ds.m_dotErr=true; }
                 m_ds.m_dotPos = DP_PACKAGE;
+                iterateAndNextNull(nodep->lhsp());
             } else {
                 m_ds.m_dotPos = DP_SCOPE;
                 iterateAndNextNull(nodep->lhsp());
                 // if (debug() >= 9) nodep->dumpTree("-dot-lho: ");
             }
+            if (m_statep->forPrimary() && isParamedClassRef(nodep->lhsp())) {
+                // Dots of paramed classes will be linked after deparametrization
+                m_ds.m_dotPos = DP_NONE;
+                return;
+            }
             if (m_ds.m_unresolved
                 && (VN_IS(nodep->lhsp(), CellRef) || VN_IS(nodep->lhsp(), CellArrayRef))) {
                 m_ds.m_unlinkedScopep = nodep->lhsp();
@@ -2517,13 +2533,24 @@ private:
         if (start) m_ds = lastStates;
     }
     virtual void visit(AstClassOrPackageRef* nodep) override {
-        UINFO(9, "   linkClassOrPackageRef " << m_ds.ascii() << "  n=" << nodep << endl);
-        if (m_ds.m_dotPos == DP_PACKAGE) {
-            // Already under dot, so this is {ClassOrPackage} Dot {ClassOrPackage}
-            // m_ds.m_dotText communicates the cell prefix between stages
-            m_ds.m_dotPos = DP_PACKAGE;
+        // Class: Recurse inside or cleanup not founds
+        // checkNoDot not appropriate, can be under a dot
+        AstNode::user5ClearTree();
+        UASSERT_OBJ(m_statep->forPrimary() || nodep->classOrPackagep(), nodep,
+                    "ClassRef has unlinked class");
+        UASSERT_OBJ(m_statep->forPrimary() || !nodep->paramsp(), nodep,
+                    "class reference parameter not removed by V3Param");
+        VL_RESTORER(m_ds);
+        VL_RESTORER(m_pinSymp);
+        {
+            // ClassRef's have pins, so track
+            if (nodep->classOrPackagep()) {
+                m_pinSymp = m_statep->getNodeSym(nodep->classOrPackagep());
+            }
+            m_ds.init(m_curSymp);
+            UINFO(4, "(Backto) Link ClassOrPackageRef: " << nodep << endl);
+            iterateChildren(nodep);
         }
-        // TODO we don't iterate pins yet, as class parameters are not supported
     }
 
     virtual void visit(AstVarRef* nodep) override {
diff --git a/src/V3Param.cpp b/src/V3Param.cpp
index 62aa66541..8c1595194 100644
--- a/src/V3Param.cpp
+++ b/src/V3Param.cpp
@@ -557,15 +557,16 @@ class ParamProcessor final {
         if ((newmodp->level() - srcModp->level()) >= (v3Global.opt.moduleRecursionDepth() - 2)) {
             cellp->v3error("Exceeded maximum --module-recursion-depth of "
                            << v3Global.opt.moduleRecursionDepth());
+            return;
         }
         // Keep tree sorted by level. Note: Different parametrizations of the same recursive module
         // end up with the same level, which we will need to fix up at the end, as we do not know
         // up front how recursive modules are expanded, and a later expansion might re-use an
         // earlier expansion (see t_recursive_module_bug_2).
-        AstNodeModule* insertp = srcModp;
-        while (insertp->nextp()
+        AstNode* insertp = srcModp;
+        while (VN_IS(insertp->nextp(), NodeModule)
                && VN_AS(insertp->nextp(), NodeModule)->level() <= newmodp->level()) {
-            insertp = VN_AS(insertp->nextp(), NodeModule);
+            insertp = insertp->nextp();
         }
         insertp->addNextHere(newmodp);
 
@@ -699,9 +700,9 @@ class ParamProcessor final {
         }
     }
 
-    void cellInterfaceCleanup(AstCell* nodep, AstNodeModule* srcModp, string& longnamer,
+    void cellInterfaceCleanup(AstPin* pinsp, AstNodeModule* srcModp, string& longnamer,
                               bool& any_overridesr, IfaceRefRefs& ifaceRefRefs) {
-        for (AstPin* pinp = nodep->pinsp(); pinp; pinp = VN_AS(pinp->nextp(), Pin)) {
+        for (AstPin* pinp = pinsp; pinp; pinp = VN_AS(pinp->nextp(), Pin)) {
             const AstVar* const modvarp = pinp->modVarp();
             if (modvarp->isIfaceRef()) {
                 AstIfaceRefDType* portIrefp = VN_CAST(modvarp->subDTypep(), IfaceRefDType);
@@ -761,8 +762,73 @@ class ParamProcessor final {
         }
     }
 
+    bool nodeDeparamCommon(AstNode* nodep, AstNodeModule*& srcModpr, AstPin* paramsp,
+                           AstPin* pinsp, bool any_overrides) {
+        // Make sure constification worked
+        // Must be a separate loop, as constant conversion may have changed some pointers.
+        // if (debug()) nodep->dumpTree(cout, "-cel2: ");
+        string longname = srcModpr->name() + "_";
+        if (debug() > 8 && paramsp) paramsp->dumpTreeAndNext(cout, "-cellparams: ");
+
+        if (srcModpr->hierBlock()) {
+            longname = parameterizedHierBlockName(srcModpr, paramsp);
+            any_overrides = longname != srcModpr->name();
+        } else {
+            for (AstPin* pinp = paramsp; pinp; pinp = VN_AS(pinp->nextp(), Pin)) {
+                cellPinCleanup(nodep, pinp, srcModpr, longname /*ref*/, any_overrides /*ref*/);
+            }
+        }
+        IfaceRefRefs ifaceRefRefs;
+        cellInterfaceCleanup(pinsp, srcModpr, longname /*ref*/, any_overrides /*ref*/,
+                             ifaceRefRefs /*ref*/);
+
+        if (!any_overrides) {
+            UINFO(8, "Cell parameters all match original values, skipping expansion.\n");
+        } else if (AstNodeModule* const paramedModp
+                   = m_hierBlocks.findByParams(srcModpr->name(), paramsp, m_modp)) {
+            paramedModp->dead(false);
+            // We need to relink the pins to the new module
+            relinkPinsByName(pinsp, paramedModp);
+            srcModpr = paramedModp;
+        } else {
+            const string newname
+                = srcModpr->hierBlock() ? longname : moduleCalcName(srcModpr, longname);
+            const ModInfo* const modInfop
+                = moduleFindOrClone(srcModpr, nodep, paramsp, newname, ifaceRefRefs);
+            // We need to relink the pins to the new module
+            relinkPinsByName(pinsp, modInfop->m_modp);
+            UINFO(8, "     Done with " << modInfop->m_modp << endl);
+            srcModpr = modInfop->m_modp;
+        }
+
+        // Delete the parameters from the cell; they're not relevant any longer.
+        if (paramsp) paramsp->unlinkFrBackWithNext()->deleteTree();
+        return any_overrides;
+    }
+
+    void cellDeparam(AstCell* nodep, AstNodeModule*& srcModpr) {
+        // Must always clone __Vrcm (recursive modules)
+        if (nodeDeparamCommon(nodep, srcModpr, nodep->paramsp(), nodep->pinsp(),
+                              nodep->recursive())) {
+            nodep->modp(srcModpr);
+            nodep->modName(srcModpr->name());
+        }
+        nodep->recursive(false);
+    }
+
+    void classRefDeparam(AstClassOrPackageRef* nodep, AstNodeModule*& srcModpr) {
+        if (nodeDeparamCommon(nodep, srcModpr, nodep->paramsp(), nullptr, false))
+            nodep->classOrPackagep(srcModpr);
+    }
+
+    void classRefDeparam(AstClassRefDType* nodep, AstNodeModule*& srcModpr) {
+        if (nodeDeparamCommon(nodep, srcModpr, nodep->paramsp(), nullptr, false))
+            nodep->classp(VN_AS(srcModpr, Class));
+    }
+
 public:
-    void cellDeparam(AstCell* nodep, AstNodeModule* modp, const string& someInstanceName) {
+    void nodeDeparam(AstNode* nodep, AstNodeModule*& srcModpr, AstNodeModule* modp,
+                     const string& someInstanceName) {
         m_modp = modp;
         // Cell: Check for parameters in the instantiation.
         // We always run this, even if no parameters, as need to look for interfaces,
@@ -772,57 +838,18 @@ public:
         if (debug() >= 10) nodep->dumpTree(cout, "-cell: ");
         // Evaluate all module constants
         V3Const::constifyParamsEdit(nodep);
-        AstNodeModule* const srcModp = nodep->modp();
-        srcModp->someInstanceName(someInstanceName + "." + nodep->name());
+        srcModpr->someInstanceName(someInstanceName + "." + nodep->name());
 
-        // Make sure constification worked
-        // Must be a separate loop, as constant conversion may have changed some pointers.
-        // if (debug()) nodep->dumpTree(cout, "-cel2: ");
-        string longname = srcModp->name() + "_";
-        bool any_overrides = false;
-        // Must always clone __Vrcm (recursive modules)
-        if (nodep->recursive()) any_overrides = true;
-        if (debug() > 8 && nodep->paramsp())
-            nodep->paramsp()->dumpTreeAndNext(cout, "-cellparams: ");
-
-        if (srcModp->hierBlock()) {
-            longname = parameterizedHierBlockName(srcModp, nodep->paramsp());
-            any_overrides = longname != srcModp->name();
+        if (auto* cellp = VN_CAST(nodep, Cell)) {
+            cellDeparam(cellp, srcModpr);
+        } else if (auto* classRefp = VN_CAST(nodep, ClassRefDType)) {
+            classRefDeparam(classRefp, srcModpr);
+        } else if (auto* classRefp = VN_CAST(nodep, ClassOrPackageRef)) {
+            classRefDeparam(classRefp, srcModpr);
         } else {
-            for (AstPin* pinp = nodep->paramsp(); pinp; pinp = VN_AS(pinp->nextp(), Pin)) {
-                cellPinCleanup(nodep, pinp, srcModp, longname /*ref*/, any_overrides /*ref*/);
-            }
-        }
-        IfaceRefRefs ifaceRefRefs;
-        cellInterfaceCleanup(nodep, srcModp, longname /*ref*/, any_overrides /*ref*/,
-                             ifaceRefRefs /*ref*/);
-
-        if (!any_overrides) {
-            UINFO(8, "Cell parameters all match original values, skipping expansion.\n");
-        } else if (AstNodeModule* const paramedModp
-                   = m_hierBlocks.findByParams(srcModp->name(), nodep->paramsp(), m_modp)) {
-            nodep->modp(paramedModp);
-            nodep->modName(paramedModp->name());
-            paramedModp->dead(false);
-            // We need to relink the pins to the new module
-            relinkPinsByName(nodep->pinsp(), paramedModp);
-        } else {
-            const string newname
-                = srcModp->hierBlock() ? longname : moduleCalcName(srcModp, longname);
-            const ModInfo* const modInfop
-                = moduleFindOrClone(srcModp, nodep, nodep->paramsp(), newname, ifaceRefRefs);
-            // Have child use this module instead.
-            nodep->modp(modInfop->m_modp);
-            nodep->modName(newname);
-            // We need to relink the pins to the new module
-            relinkPinsByName(nodep->pinsp(), modInfop->m_modp);
-            UINFO(8, "     Done with " << modInfop->m_modp << endl);
+            nodep->v3fatalSrc("Expected module parametrization");
         }
 
-        nodep->recursive(false);
-
-        // Delete the parameters from the cell; they're not relevant any longer.
-        if (nodep->paramsp()) nodep->paramsp()->unlinkFrBackWithNext()->deleteTree();
         UINFO(8, "     Done with " << nodep << endl);
         // if (debug() >= 10)
         // v3Global.rootp()->dumpTreeFile(v3Global.debugFilename("param-out.tree"));
@@ -854,7 +881,8 @@ class ParamVisitor final : public VNVisitor {
     bool m_iterateModule = false;  // Iterating module body
     string m_generateHierName;  // Generate portion of hierarchy name
     string m_unlinkedTxt;  // Text for AstUnlinkedRef
-    std::deque<AstCell*> m_cellps;  // Cells left to process (in current module)
+    std::multimap<bool, AstNode*> m_cellps;  // Cells left to process (in current module)
+    std::multimap<int, AstNodeModule*> m_workQueue;  // Modules left to process
 
     // Map from AstNodeModule to set of all AstNodeModules that instantiates it.
     std::unordered_map<AstNodeModule*, std::unordered_set<AstNodeModule*>> m_parentps;
@@ -887,32 +915,40 @@ class ParamVisitor final : public VNVisitor {
 
             // Process interface cells, then non-interface cells, which may reference an interface
             // cell.
-            for (bool doInterface : {true, false}) {
-                for (AstCell* const cellp : m_cellps) {
-                    if (doInterface != VN_IS(cellp->modp(), Iface)) continue;
+            while (!m_cellps.empty()) {
+                const auto itm = m_cellps.cbegin();
+                AstNode* const cellp = itm->second;
+                m_cellps.erase(itm);
 
-                    // Visit parameters in the instantiation.
-                    iterateChildren(cellp);
-
-                    // Update path
-                    string someInstanceName(modp->someInstanceName());
-                    if (const string* const genHierNamep = cellp->user5u().to<string*>()) {
-                        someInstanceName += *genHierNamep;
-                        cellp->user5p(nullptr);
-                        VL_DO_DANGLING(delete genHierNamep, genHierNamep);
-                    }
-
-                    // Apply parameter specialization
-                    m_processor.cellDeparam(cellp, modp, someInstanceName);
-
-                    // Add the (now potentially specialized) child module to the work queue
-                    workQueue.emplace(cellp->modp()->level(), cellp->modp());
-
-                    // Add to the hierarchy registry
-                    m_parentps[cellp->modp()].insert(modp);
+                AstNodeModule* srcModp = nullptr;
+                if (const auto* modCellp = VN_CAST(cellp, Cell)) {
+                    srcModp = modCellp->modp();
+                } else if (const auto* classRefp = VN_CAST(cellp, ClassOrPackageRef)) {
+                    srcModp = classRefp->classOrPackagep();
+                } else if (const auto* classRefp = VN_CAST(cellp, ClassRefDType)) {
+                    srcModp = classRefp->classp();
+                } else {
+                    cellp->v3fatalSrc("Expected module parametrization");
                 }
+
+                // Update path
+                string someInstanceName(modp->someInstanceName());
+                if (const string* const genHierNamep = cellp->user5u().to<string*>()) {
+                    someInstanceName += *genHierNamep;
+                    cellp->user5p(nullptr);
+                    VL_DO_DANGLING(delete genHierNamep, genHierNamep);
+                }
+
+                // Apply parameter specialization
+                m_processor.nodeDeparam(cellp, srcModp /* ref */, modp, someInstanceName);
+
+                // Add the (now potentially specialized) child module to the work queue
+                workQueue.emplace(srcModp->level(), srcModp);
+
+                // Add to the hierarchy registry
+                m_parentps[srcModp].insert(modp);
             }
-            m_cellps.clear();
+            if (workQueue.empty()) std::swap(workQueue, m_workQueue);
         } while (!workQueue.empty());
 
         m_iterateModule = false;
@@ -930,25 +966,24 @@ class ParamVisitor final : public VNVisitor {
         if (modp->level() <= maxParentLevel) modp->level(maxParentLevel + 1);
     }
 
+    // A generic visitor for cells and class refs
+    void visitCellOrClassRef(AstNode* nodep, bool isIface) {
+        // Must do ifaces first, so push to list and do in proper order
+        string* const genHierNamep = new string{m_generateHierName};
+        nodep->user5p(genHierNamep);
+        // Visit parameters in the instantiation.
+        iterateChildren(nodep);
+        m_cellps.emplace(!isIface, nodep);
+    }
+
     // VISITORS
     virtual void visit(AstNodeModule* nodep) override {
         if (nodep->recursiveClone()) nodep->dead(true);  // Fake, made for recursive elimination
         if (nodep->dead()) return;  // Marked by LinkDot (and above)
 
-        // Warn on unsupported parametrised class
-        if (VN_IS(nodep, Class)) {
-            for (AstNode* stmtp = nodep->stmtsp(); stmtp; stmtp = stmtp->nextp()) {
-                if (const AstVar* const varp = VN_CAST(stmtp, Var)) {
-                    if (varp->isParam()) {
-                        varp->v3warn(E_UNSUPPORTED, "Unsupported: class parameters");
-                    }
-                }
-            }
-        }
-
         if (m_iterateModule) {  // Iterating body
             UINFO(4, " MOD-under-MOD.  " << nodep << endl);
-            iterateChildren(nodep);
+            m_workQueue.emplace(nodep->level(), nodep);  // Delay until current module is done
             return;
         }
 
@@ -961,19 +996,10 @@ class ParamVisitor final : public VNVisitor {
     }
 
     virtual void visit(AstCell* nodep) override {
-        // Must do ifaces first, so push to list and do in proper order
-        string* const genHierNamep = new string(m_generateHierName);
-        nodep->user5p(genHierNamep);
-        m_cellps.push_back(nodep);
-    }
-
-    virtual void visit(AstClassRefDType* nodep) override {
-        if (nodep->paramsp()) {
-            nodep->paramsp()->v3warn(E_UNSUPPORTED, "Unsupported: parameterized classes");
-            pushDeletep(nodep->paramsp()->unlinkFrBackWithNext());
-        }
-        iterateChildren(nodep);
+        visitCellOrClassRef(nodep, VN_IS(nodep->modp(), Iface));
     }
+    virtual void visit(AstClassRefDType* nodep) override { visitCellOrClassRef(nodep, false); }
+    virtual void visit(AstClassOrPackageRef* nodep) override { visitCellOrClassRef(nodep, false); }
 
     // Make sure all parameters are constantified
     virtual void visit(AstVar* nodep) override {
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 824d66beb..a9f784e06 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -2438,6 +2438,17 @@ private:
         // though causes problems with t_class_forward.v, so for now avoided
         // userIterateChildren(nodep->classp(), nullptr);
     }
+    virtual void visit(AstClassOrPackageRef* nodep) override {
+        if (nodep->didWidthAndSet()) return;
+        userIterateChildren(nodep, nullptr);
+    }
+    virtual void visit(AstDot* nodep) override {
+        // We can only reach this from constify called during V3Param (so before linkDotParam)
+        // ... #(Cls#(...)::...) ...
+        //                ^^~~~ this is our DOT
+        nodep->v3warn(E_UNSUPPORTED, "dotted expressions in parameters\n"
+                                         << nodep->warnMore() << "... Suggest use a typedef");
+    }
     virtual void visit(AstClassExtends* nodep) override {
         if (nodep->didWidthAndSet()) return;
         if (VN_IS(nodep->childDTypep(), ClassRefDType)) {
diff --git a/test_regress/t/t_class_param.out b/test_regress/t/t_class_param.out
deleted file mode 100644
index 442cfc01e..000000000
--- a/test_regress/t/t_class_param.out
+++ /dev/null
@@ -1,30 +0,0 @@
-%Error-UNSUPPORTED: t/t_class_param.v:40:11: Unsupported: parameterized classes
-                                           : ... In instance t
-   40 |    Cls #(.PBASE(4)) c4;
-      |           ^~~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_class_param.v:42:12: Unsupported: parameterized classes
-                                           : ... In instance t
-   42 |    Wrap #(.P(16)) w16;
-      |            ^
-%Error-UNSUPPORTED: t/t_class_param.v:13:24: Unsupported: class parameters
-                                           : ... In instance t
-   13 | class Wrap #(parameter P = 13);
-      |                        ^
-%Error-UNSUPPORTED: t/t_class_param.v:21:15: Unsupported: class parameters
-                                           : ... In instance t
-   21 |    localparam PMINUS1 = P - 1;   
-      |               ^~~~~~~
-%Error-UNSUPPORTED: t/t_class_param.v:20:17: Unsupported: parameterized classes
-                                           : ... In instance t
-   20 |    Cls#(PMINUS1 + 1) c1;
-      |                 ^
-%Error-UNSUPPORTED: t/t_class_param.v:24:23: Unsupported: class parameters
-                                           : ... In instance t
-   24 | class Cls #(parameter PBASE = 12);
-      |                       ^~~~~
-%Error-UNSUPPORTED: t/t_class_param.v:35:14: Unsupported: parameterized classes
-                                           : ... In instance t
-   35 | typedef Cls#(8) Cls8_t;
-      |              ^
-%Error: Exiting due to
diff --git a/test_regress/t/t_class_param.pl b/test_regress/t/t_class_param.pl
index 2ad4a887d..aabcde63e 100755
--- a/test_regress/t/t_class_param.pl
+++ b/test_regress/t/t_class_param.pl
@@ -11,13 +11,11 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 scenarios(simulator => 1);
 
 compile(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
     );
 
 execute(
     check_finished => 1,
-    ) if !$Self->{vlt_all};
+    );
 
 ok(1);
 1;
diff --git a/test_regress/t/t_class_param.v b/test_regress/t/t_class_param.v
index 0fc61cb76..99740abb7 100644
--- a/test_regress/t/t_class_param.v
+++ b/test_regress/t/t_class_param.v
@@ -21,6 +21,17 @@ class Wrap #(parameter P = 13);
    localparam PMINUS1 = P - 1;  // Checking works when last
 endclass
 
+class Wrap2 #(parameter P = 35);
+   function int get_p;
+      return c1.get_p();
+   endfunction
+   function new;
+      c1 = new;
+   endfunction
+   Wrap#(PMINUS1 + 1) c1;
+   localparam PMINUS1 = P - 1;  // Checking works when last
+endclass
+
 class Cls #(parameter PBASE = 12);
    bit [PBASE-1:0] member;
    function bit [PBASE-1:0] get_member;
@@ -40,11 +51,13 @@ module t (/*AUTOARG*/);
    Cls #(.PBASE(4)) c4;
    Cls8_t c8;
    Wrap #(.P(16)) w16;
+   Wrap2 #(.P(32)) w32;
    initial begin
       c12 = new;
       c4 = new;
       c8 = new;
       w16 = new;
+      w32 = new;
       if (Cls#()::PBASE != 12) $stop;
       if (Cls#(4)::PBASE != 4) $stop;
       if (Cls8_t::PBASE != 8) $stop;
@@ -65,6 +78,7 @@ module t (/*AUTOARG*/);
       if (c4.get_p() != 4) $stop;
       if (c8.get_p() != 8) $stop;
       if (w16.get_p() != 16) $stop;
+      if (w32.get_p() != 32) $stop;
 
       // verilator lint_off WIDTH
       c12.member = 32'haaaaaaaa;
diff --git a/test_regress/t/t_class_param_circ_bad.out b/test_regress/t/t_class_param_circ_bad.out
new file mode 100644
index 000000000..35b6ce09a
--- /dev/null
+++ b/test_regress/t/t_class_param_circ_bad.out
@@ -0,0 +1,5 @@
+%Error: t/t_class_param_circ_bad.v:14:4: Exceeded maximum --module-recursion-depth of 100
+                                       : ... In instance t
+   14 |    ClsA #(PARAM+1) a;
+      |    ^~~~
+%Error: Internal Error: ../V3Param.cpp:#: should find just-made module
diff --git a/test_regress/t/t_class_param_circ_bad.pl b/test_regress/t/t_class_param_circ_bad.pl
new file mode 100755
index 000000000..c35c8bc93
--- /dev/null
+++ b/test_regress/t/t_class_param_circ_bad.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2022 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+lint(
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_class_param_circ_bad.v b/test_regress/t/t_class_param_circ_bad.v
new file mode 100644
index 000000000..3ebe10df8
--- /dev/null
+++ b/test_regress/t/t_class_param_circ_bad.v
@@ -0,0 +1,21 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2022 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+typedef class ClsB;
+
+class ClsA #(parameter PARAM = 12);
+   ClsB #(PARAM+1) b;
+endclass
+
+class ClsB #(parameter PARAM = 12);
+   ClsA #(PARAM+1) a;
+endclass
+
+module t (/*AUTOARG*/);
+
+   ClsA #(.PARAM(15)) c;  // Bad param name
+
+endmodule
diff --git a/test_regress/t/t_class_param_extends.pl b/test_regress/t/t_class_param_extends.pl
new file mode 100755
index 000000000..1aa73f80a
--- /dev/null
+++ b/test_regress/t/t_class_param_extends.pl
@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2022 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+compile(
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_class_param_extends.v b/test_regress/t/t_class_param_extends.v
new file mode 100644
index 000000000..1c1078ea7
--- /dev/null
+++ b/test_regress/t/t_class_param_extends.v
@@ -0,0 +1,52 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2022 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+// Code your testbench here
+// or browse Examples
+class Base #(parameter PBASE = 12);
+   bit [PBASE-1:0] member;
+  function bit [PBASE-1:0] get_member;
+      return member;
+   endfunction
+   function int get_p;
+      return PBASE;
+   endfunction
+endclass
+
+class Cls #(parameter P = 13) extends Base #(P);
+endclass
+
+typedef Cls#(8) Cls8_t;
+
+// See also t_class_param_mod.v
+
+module t (/*AUTOARG*/);
+
+   Cls #(.P(4)) c4;
+   Cls8_t c8;
+
+   initial begin
+      c4 = new;
+      c8 = new;
+      if (c4.PBASE != 4) $stop;
+      if (c8.PBASE != 8) $stop;
+      if (c4.get_p() != 4) $stop;
+      if (c8.get_p() != 8) $stop;
+      // verilator lint_off WIDTH
+      c4.member = 32'haaaaaaaa;
+      c8.member = 32'haaaaaaaa;
+      // verilator lint_on WIDTH
+      if (c4.member != 4'ha) $stop;
+      if (c4.get_member() != 4'ha) $stop;
+      if (c8.member != 8'haa) $stop;
+      if (c8.get_member() != 8'haa) $stop;
+      $display("c4 = %s", $sformatf("%p", c4));
+      if ($sformatf("%p", c4) != "'{member:'ha}") $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule
diff --git a/test_regress/t/t_class_param_mod.pl b/test_regress/t/t_class_param_mod.pl
index a2ed99042..aabcde63e 100755
--- a/test_regress/t/t_class_param_mod.pl
+++ b/test_regress/t/t_class_param_mod.pl
@@ -11,12 +11,11 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 scenarios(simulator => 1);
 
 compile(
-    fails => $Self->{vlt_all},
     );
 
 execute(
     check_finished => 1,
-    ) if !$Self->{vlt_all};
+    );
 
 ok(1);
 1;
diff --git a/test_regress/t/t_class_param_mod.v b/test_regress/t/t_class_param_mod.v
index 67065e2d7..a57ba7316 100644
--- a/test_regress/t/t_class_param_mod.v
+++ b/test_regress/t/t_class_param_mod.v
@@ -32,17 +32,30 @@ class Wrap #(parameter P = 13);
    localparam PMINUS1 = P - 1;  // Checking works when last
 endclass
 
+class Wrap2 #(parameter P = 35);
+   function int get_p;
+      return c1.get_p();
+   endfunction
+   function new;
+      c1 = new;
+   endfunction
+   Wrap#(PMINUS1 + 1) c1;
+   localparam PMINUS1 = P - 1;  // Checking works when last
+endclass
+
    typedef Cls#(8) Cls8_t;
 
    Cls c12;
    Cls #(.PBASE(4)) c4;
    Cls8_t c8;
    Wrap #(.P(16)) w16;
+   Wrap2 #(.P(32)) w32;
    initial begin
       c12 = new;
       c4 = new;
       c8 = new;
       w16 = new;
+      w32 = new;
       if (Cls#()::PBASE != 12) $stop;
       if (Cls#(4)::PBASE != 4) $stop;
       if (Cls8_t::PBASE != 8) $stop;
@@ -63,6 +76,7 @@ endclass
       if (c4.get_p() != 4) $stop;
       if (c8.get_p() != 8) $stop;
       if (w16.get_p() != 16) $stop;
+      if (w32.get_p() != 32) $stop;
 
       // verilator lint_off WIDTH
       c12.member = 32'haaaaaaaa;
diff --git a/test_regress/t/t_class_param_nconst_bad.out b/test_regress/t/t_class_param_nconst_bad.out
index 100f930d8..812399530 100644
--- a/test_regress/t/t_class_param_nconst_bad.out
+++ b/test_regress/t/t_class_param_nconst_bad.out
@@ -1,10 +1,9 @@
-%Error-UNSUPPORTED: t/t_class_param_nconst_bad.v:12:11: Unsupported: parameterized classes
-                                                      : ... In instance t
+%Error: t/t_class_param_nconst_bad.v:12:17: Expecting expression to be constant, but can't convert a RAND to constant.
+                                          : ... In instance t
+   12 |    Cls #(.PARAM($random)) c;   
+      |                 ^~~~~~~
+%Error: t/t_class_param_nconst_bad.v:12:11: Can't convert defparam value to constant: Param 'PARAM' of 'Cls'
+                                          : ... In instance t
    12 |    Cls #(.PARAM($random)) c;   
       |           ^~~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_class_param_nconst_bad.v:7:23: Unsupported: class parameters
-                                                     : ... In instance t
-    7 | class Cls #(parameter PARAM = 12);
-      |                       ^~~~~
 %Error: Exiting due to
diff --git a/test_regress/t/t_class_param_nested_bad.out b/test_regress/t/t_class_param_nested_bad.out
new file mode 100644
index 000000000..ce4a30bc0
--- /dev/null
+++ b/test_regress/t/t_class_param_nested_bad.out
@@ -0,0 +1,10 @@
+%Error-UNSUPPORTED: t/t_class_param_nested_bad.v:51:23: dotted expressions in parameters
+                                                      : ... In instance t
+                                                      : ... Suggest use a typedef
+   51 |    Wrap2 #(Wrap#(19)::PBASE * 2) w38;
+      |                       ^~~~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error: Internal Error: t/t_class_param_nested_bad.v:51:29: ../V3Width.cpp:#: Node has no type
+                                                          : ... In instance t
+   51 |    Wrap2 #(Wrap#(19)::PBASE * 2) w38;
+      |                             ^
diff --git a/test_regress/t/t_class_param_nested_bad.pl b/test_regress/t/t_class_param_nested_bad.pl
new file mode 100755
index 000000000..c35c8bc93
--- /dev/null
+++ b/test_regress/t/t_class_param_nested_bad.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2022 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+lint(
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_class_param_nested_bad.v b/test_regress/t/t_class_param_nested_bad.v
new file mode 100644
index 000000000..ec65b3e09
--- /dev/null
+++ b/test_regress/t/t_class_param_nested_bad.v
@@ -0,0 +1,64 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2022 by Arkadiusz Kozdra.
+// SPDX-License-Identifier: CC0-1.0
+
+typedef class Cls;
+
+class Wrap #(parameter P = 13);
+   function int get_p;
+      return c1.get_p();
+   endfunction
+   function new;
+      c1 = new;
+   endfunction
+   Cls#(PMINUS1 + 1) c1;
+   localparam PMINUS1 = P - 1;  // Checking works when last
+endclass
+
+class Wrap2 #(parameter P = 35);
+   function int get_p;
+      return c1.get_p();
+   endfunction
+   function new;
+      c1 = new;
+   endfunction
+   Wrap#(PMINUS1 + 1) c1;
+   localparam PMINUS1 = P - 1;  // Checking works when last
+endclass
+
+class Cls #(parameter PBASE = 12);
+   bit [PBASE-1:0] member;
+   function bit [PBASE-1:0] get_member;
+      return member;
+   endfunction
+   static function int get_p;
+      return PBASE;
+   endfunction
+   typedef enum { E_PBASE = PBASE } enum_t;
+endclass
+
+typedef Cls#(8) Cls8_t;
+
+module t (/*AUTOARG*/);
+
+   Cls c12;
+   Cls #(.PBASE(4)) c4;
+   Cls8_t c8;
+   Wrap #(.P(16)) w16;
+   Wrap2 #(.P(32)) w32;
+   Wrap2 #(Wrap#(19)::PBASE * 2) w38;
+   initial begin
+      c12 = new;
+      c4 = new;
+      c8 = new;
+      w16 = new;
+      w32 = new;
+      w38 = new;
+      if (w38.get_p() != 38) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule
diff --git a/test_regress/t/t_class_param_pkg.out b/test_regress/t/t_class_param_pkg.out
deleted file mode 100644
index a01b5aed6..000000000
--- a/test_regress/t/t_class_param_pkg.out
+++ /dev/null
@@ -1,30 +0,0 @@
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:43:16: Unsupported: parameterized classes
-                                               : ... In instance t
-   43 |    Pkg::Cls #(.PBASE(4)) c4;
-      |                ^~~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:45:17: Unsupported: parameterized classes
-                                               : ... In instance t
-   45 |    Pkg::Wrap #(.P(16)) w16;
-      |                 ^
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:14:27: Unsupported: class parameters
-                                               : ... In instance t
-   14 |    class Wrap #(parameter P = 13);
-      |                           ^
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:22:18: Unsupported: class parameters
-                                               : ... In instance t
-   22 |       localparam PMINUS1 = P - 1;   
-      |                  ^~~~~~~
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:21:20: Unsupported: parameterized classes
-                                               : ... In instance t
-   21 |       Cls#(PMINUS1 + 1) c1;
-      |                    ^
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:25:26: Unsupported: class parameters
-                                               : ... In instance t
-   25 |    class Cls #(parameter PBASE = 12);
-      |                          ^~~~~
-%Error-UNSUPPORTED: t/t_class_param_pkg.v:36:22: Unsupported: parameterized classes
-                                               : ... In instance t
-   36 |    typedef Pkg::Cls#(8) Cls8_t;
-      |                      ^
-%Error: Exiting due to
diff --git a/test_regress/t/t_class_param_pkg.pl b/test_regress/t/t_class_param_pkg.pl
index 2ad4a887d..aabcde63e 100755
--- a/test_regress/t/t_class_param_pkg.pl
+++ b/test_regress/t/t_class_param_pkg.pl
@@ -11,13 +11,11 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 scenarios(simulator => 1);
 
 compile(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
     );
 
 execute(
     check_finished => 1,
-    ) if !$Self->{vlt_all};
+    );
 
 ok(1);
 1;
diff --git a/test_regress/t/t_class_param_pkg.v b/test_regress/t/t_class_param_pkg.v
index 4c53244f8..e311756c2 100644
--- a/test_regress/t/t_class_param_pkg.v
+++ b/test_regress/t/t_class_param_pkg.v
@@ -22,6 +22,17 @@ package Pkg;
       localparam PMINUS1 = P - 1;  // Checking works when last
    endclass
 
+   class Wrap2 #(parameter P = 35);
+      function int get_p;
+         return c1.get_p();
+      endfunction
+      function new;
+         c1 = new;
+      endfunction
+      Wrap#(PMINUS1 + 1) c1;
+      localparam PMINUS1 = P - 1;  // Checking works when last
+   endclass
+
    class Cls #(parameter PBASE = 12);
       bit [PBASE-1:0] member;
       function bit [PBASE-1:0] get_member;
@@ -43,11 +54,13 @@ module t (/*AUTOARG*/);
    Pkg::Cls #(.PBASE(4)) c4;
    Pkg::Cls8_t c8;
    Pkg::Wrap #(.P(16)) w16;
+   Pkg::Wrap2 #(.P(32)) w32;
    initial begin
       c12 = new;
       c4 = new;
       c8 = new;
       w16 = new;
+      w32 = new;
       if (Pkg::Cls#()::PBASE != 12) $stop;
       if (Pkg::Cls#(4)::PBASE != 4) $stop;
       if (Pkg::Cls8_t::PBASE != 8) $stop;
@@ -68,6 +81,7 @@ module t (/*AUTOARG*/);
       if (c4.get_p() != 4) $stop;
       if (c8.get_p() != 8) $stop;
       if (w16.get_p() != 16) $stop;
+      if (w32.get_p() != 32) $stop;
 
       // verilator lint_off WIDTH
       c12.member = 32'haaaaaaaa;
diff --git a/test_regress/t/t_class_vparam.out b/test_regress/t/t_class_vparam.out
deleted file mode 100644
index 7c4a4ba3d..000000000
--- a/test_regress/t/t_class_vparam.out
+++ /dev/null
@@ -1,18 +0,0 @@
-%Error-UNSUPPORTED: t/t_class_vparam.v:11:26: Unsupported: parameterized classes
-                                            : ... In instance t
-   11 | typedef paramed_class_t#(real, 1) paramed_class_double_t;
-      |                          ^~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_class_vparam.v:13:56: Unsupported: class parameters
-                                            : ... In instance t
-   13 | virtual class vclass #(type CTYPE_t = arg_class_t, int I = 0);
-      |                                                        ^
-%Error-UNSUPPORTED: t/t_class_vparam.v:14:58: Unsupported: parameterized classes
-                                            : ... In instance t
-   14 |    pure virtual function void funcname(paramed_class_t #(CTYPE_t) v);
-      |                                                          ^~~~~~~
-%Error-UNSUPPORTED: t/t_class_vparam.v:17:46: Unsupported: class parameters
-                                            : ... In instance t
-   17 | class paramed_class_t #(type TYPE = int, int I = 0);
-      |                                              ^
-%Error: Exiting due to
diff --git a/test_regress/t/t_class_vparam.pl b/test_regress/t/t_class_vparam.pl
index c6e10f70b..c81275cdf 100755
--- a/test_regress/t/t_class_vparam.pl
+++ b/test_regress/t/t_class_vparam.pl
@@ -11,13 +11,11 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 scenarios(simulator => 1);
 
 compile(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
     );
 
 execute(
     check_finished => 1,
-    ) if !$Self->{vlt_all};
+    );
 
 ok(1);
 1;
diff --git a/test_regress/t/t_class_vparam.v b/test_regress/t/t_class_vparam.v
index 9f19c609a..660dbb5fa 100644
--- a/test_regress/t/t_class_vparam.v
+++ b/test_regress/t/t_class_vparam.v
@@ -8,16 +8,18 @@
 
 typedef class paramed_class_t;
 typedef class arg_class_t;
-typedef paramed_class_t#(real, 1) paramed_class_double_t;
+typedef paramed_class_t#(logic[3:0], 1) paramed_class_logic4_t;
 
 virtual class vclass #(type CTYPE_t = arg_class_t, int I = 0);
    pure virtual function void funcname(paramed_class_t #(CTYPE_t) v);
 endclass
 
 class paramed_class_t #(type TYPE = int, int I = 0);
+   TYPE memb;
 endclass
 
 class arg_class_t;
+   int ifield;
 endclass
 
 module t (/*AUTOARG*/
@@ -26,7 +28,15 @@ module t (/*AUTOARG*/
    );
    input clk;
 
-   always @ (posedge clk) begin
+   vclass vir;
+   paramed_class_t#(arg_class_t) argu;
+
+   initial begin
+      argu = new;
+      argu.memb = new;
+      argu.memb.ifield = 1234;
+      // vir.funcname(argu);
+      if (argu.memb.ifield != 1234) $stop;
       $write("*-* All Finished *-*\n");
       $finish;
    end