diff --git a/src/V3AstNodeDType.h b/src/V3AstNodeDType.h
index 81c93c04c..376b30011 100644
--- a/src/V3AstNodeDType.h
+++ b/src/V3AstNodeDType.h
@@ -666,16 +666,12 @@ class AstDefImplicitDType final : public AstNodeDType {
     // After link, these become typedefs
     // @astgen op1 := childDTypep : Optional[AstNodeDType]
     string m_name;
-    void* m_containerp;  // In what scope is the name unique, so we can know what are duplicate
-                         // definitions (arbitrary value)
     const int m_uniqueNum;
 
 public:
-    AstDefImplicitDType(FileLine* fl, const string& name, void* containerp, VFlagChildDType,
-                        AstNodeDType* dtp)
+    AstDefImplicitDType(FileLine* fl, const string& name, VFlagChildDType, AstNodeDType* dtp)
         : ASTGEN_SUPER_DefImplicitDType(fl)
         , m_name{name}
-        , m_containerp{containerp}
         , m_uniqueNum{uniqueNumInc()} {
         childDTypep(dtp);  // Only for parser
         dtypep(nullptr);  // V3Width will resolve
@@ -683,7 +679,6 @@ public:
     AstDefImplicitDType(const AstDefImplicitDType& other)
         : AstNodeDType(other)
         , m_name(other.m_name)
-        , m_containerp(other.m_containerp)
         , m_uniqueNum(uniqueNumInc()) {}
     ASTGEN_MEMBERS_AstDefImplicitDType;
     int uniqueNum() const { return m_uniqueNum; }
@@ -696,7 +691,6 @@ public:
     AstNodeDType* subDTypep() const override VL_MT_STABLE {
         return dtypep() ? dtypep() : childDTypep();
     }
-    void* containerp() const { return m_containerp; }
     // METHODS
     // op1 = Range of variable
     AstNodeDType* dtypeSkipRefp() const { return dtypep()->skipRefp(); }
diff --git a/src/V3LinkParse.cpp b/src/V3LinkParse.cpp
index d2860ff58..c48830a09 100644
--- a/src/V3LinkParse.cpp
+++ b/src/V3LinkParse.cpp
@@ -42,7 +42,7 @@ class LinkParseVisitor final : public VNVisitor {
     const VNUser2InUse m_inuser2;
 
     // TYPES
-    using ImplTypedefMap = std::map<const std::pair<void*, std::string>, AstTypedef*>;
+    using ImplTypedefMap = std::map<std::string, AstTypedef*>;
 
     // STATE
     AstVar* m_varp = nullptr;  // Variable we're under
@@ -498,14 +498,14 @@ class LinkParseVisitor final : public VNVisitor {
         cleanFileline(nodep);
         UINFO(8, "   DEFIMPLICIT " << nodep << endl);
         // Must remember what names we've already created, and combine duplicates
-        // so that for "var enum {...} a,b" a & b will share a common typedef
-        // Unique name space under each containerp() so that an addition of
+        // so that for "var enum {...} a,b" a & b will share a common typedef.
+        // Change to unique name space per module so that an addition of
         // a new type won't change every verilated module.
         AstTypedef* defp = nullptr;
-        const ImplTypedefMap::iterator it
-            = m_implTypedef.find(std::make_pair(nodep->containerp(), nodep->name()));
+        const ImplTypedefMap::iterator it = m_implTypedef.find(nodep->name());
         if (it != m_implTypedef.end()) {
             defp = it->second;
+            UINFO(9, "Reused impltypedef " << nodep << "  -->  " << defp << endl);
         } else {
             // Definition must be inserted right after the variable (etc) that needed it
             // AstVar, AstTypedef, AstNodeFTask are common containers
@@ -526,7 +526,11 @@ class LinkParseVisitor final : public VNVisitor {
             } else {
                 defp = new AstTypedef{nodep->fileline(), nodep->name(), nullptr, VFlagChildDType{},
                                       dtypep};
-                m_implTypedef.emplace(std::make_pair(nodep->containerp(), defp->name()), defp);
+                m_implTypedef.emplace(defp->name(), defp);
+                // Rename so that name doesn't change if a type is added/removed elsewhere
+                // But the m_implTypedef is stil by old name so we can find it for next new lookups
+                defp->name("__typeimpmod" + cvtToStr(m_implTypedef.size()));
+                UINFO(9, "New impltypedef " << defp << endl);
                 backp->addNextHere(defp);
             }
         }
@@ -618,6 +622,7 @@ class LinkParseVisitor final : public VNVisitor {
         VL_RESTORER(m_genblkAbove);
         VL_RESTORER(m_genblkNum);
         VL_RESTORER(m_beginDepth);
+        VL_RESTORER(m_implTypedef);
         VL_RESTORER(m_lifetime);
         VL_RESTORER(m_lifetimeAllowed);
         {
@@ -630,6 +635,7 @@ class LinkParseVisitor final : public VNVisitor {
             m_genblkAbove = 0;
             m_genblkNum = 0;
             m_beginDepth = 0;
+            m_implTypedef.clear();
             m_valueModp = nodep;
             m_lifetime = nodep->lifetime();
             m_lifetimeAllowed = VN_IS(nodep, Class);
diff --git a/src/V3ParseImp.cpp b/src/V3ParseImp.cpp
index 8e6613fe1..b33972145 100644
--- a/src/V3ParseImp.cpp
+++ b/src/V3ParseImp.cpp
@@ -749,7 +749,12 @@ int V3ParseImp::tokenToBison() {
 // V3ParseBisonYYSType functions
 
 std::ostream& operator<<(std::ostream& os, const V3ParseBisonYYSType& rhs) {
-    os << "TOKEN {" << rhs.fl->filenameLetters() << rhs.fl->asciiLineCol() << "}";
+    os << "TOKEN {";
+    if (VL_UNCOVERABLE(!rhs.fl))
+        os << "%E-null-fileline";
+    else
+        os << rhs.fl->filenameLetters() << rhs.fl->asciiLineCol();
+    os << "}";
     os << "=" << rhs.token << " " << V3ParseImp::tokenName(rhs.token);
     if (rhs.token == yaID__ETC  //
         || rhs.token == yaID__CC  //
diff --git a/src/verilog.y b/src/verilog.y
index 5c69afffb..08025f727 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -108,7 +108,7 @@ public:
     int m_pinNum = -1;  // Pin number currently parsing
     std::stack<int> m_pinStack;  // Queue of pin numbers being parsed
 
-    static int s_modTypeImpNum;  // Implicit type number, incremented each module
+    static int s_typeImpNum;  // Implicit type number, incremented each module
 
     // CONSTRUCTORS
     V3ParseGrammar() {}
@@ -300,7 +300,7 @@ public:
 const VBasicDTypeKwd LOGIC = VBasicDTypeKwd::LOGIC;  // Shorthand "LOGIC"
 const VBasicDTypeKwd LOGIC_IMPLICIT = VBasicDTypeKwd::LOGIC_IMPLICIT;
 
-int V3ParseGrammar::s_modTypeImpNum = 0;
+int V3ParseGrammar::s_typeImpNum = 0;
 
 //======================================================================
 // Macro functions
@@ -2233,12 +2233,12 @@ data_typeNoRef<nodeDTypep>:             // ==IEEE: data_type, excluding class_ty
         |       struct_unionDecl packed_dimensionListE
                         { $$ = GRAMMARP->createArray(
                                    new AstDefImplicitDType{$1->fileline(),
-                                                           "__typeimpsu" + cvtToStr(GRAMMARP->s_modTypeImpNum++),
-                                                           SYMP, VFlagChildDType{}, $1}, $2, true); }
+                                                           "__typeimpsu" + cvtToStr(GRAMMARP->s_typeImpNum++),
+                                                           VFlagChildDType{}, $1}, $2, true); }
         |       enumDecl
                         { $$ = new AstDefImplicitDType{$1->fileline(),
-                                                       "__typeimpenum" + cvtToStr(GRAMMARP->s_modTypeImpNum++),
-                                                       SYMP, VFlagChildDType{}, $1}; }
+                                                       "__typeimpenum" + cvtToStr(GRAMMARP->s_typeImpNum++),
+                                                       VFlagChildDType{}, $1}; }
         |       ySTRING
                         { $$ = new AstBasicDType{$1, VBasicDTypeKwd::STRING}; }
         |       yCHANDLE
diff --git a/test_regress/t/t_typename.out b/test_regress/t/t_typename.out
index 133f56582..f8ebfd10d 100644
--- a/test_regress/t/t_typename.out
+++ b/test_regress/t/t_typename.out
@@ -20,7 +20,7 @@
 "int$[$:3]" ==? "int$[$:3]"
 "bit$[]" ==? "bit$[]"
 
-"enum{A=32'h0;B=32'h1;C=32'h63;}A::__typeimpenum1" ==? "enum{A=32'sd0,B=32'sd1,C=32'sd99}A::<unspecified>"
+"enum{A=32'h0;B=32'h1;C=32'h63;}A::__typeimpmod1" ==? "enum{A=32'sd0,B=32'sd1,C=32'sd99}A::<unspecified>"
 "struct{bit A;bit B;}t.AB_t" ==? "struct{bit A;bit B;}<some_have_typename>"
 "struct{bit A;bit B;}t.AB_t$[0:9]" ==? "struct{bit A;bit B;}top.AB_t$[0:9]"
 "union{bit A;bit B;}t.UAB_t" ==? "union{bit A;bit B;}"
diff --git a/test_regress/t/t_typename.py b/test_regress/t/t_typename.py
index ab5dca066..1a1bebba6 100755
--- a/test_regress/t/t_typename.py
+++ b/test_regress/t/t_typename.py
@@ -9,7 +9,7 @@
 
 import vltest_bootstrap
 
-test.scenarios('simulator')
+test.scenarios('simulator_st')
 
 test.compile()