diff --git a/include/std.sv b/include/std.sv
new file mode 100644
index 000000000..7b27bc98b
--- /dev/null
+++ b/include/std.sv
@@ -0,0 +1,106 @@
+// DESCRIPTION: Verilator: built-in packages and classes
+//
+// Code available from: https://verilator.org
+//
+//*************************************************************************
+//
+// 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
+//
+//*************************************************************************
+
+// verilator lint_off DECLFILENAME
+// verilator lint_off TIMESCALEMOD
+// verilator lint_off UNUSEDSIGNAL
+package std;
+    class mailbox #(type T);
+        protected int m_bound;
+        protected T m_queue[$];
+
+        function new(int bound = 0);
+            m_bound = bound;
+        endfunction
+
+        function int num();
+            return m_queue.size();
+        endfunction
+
+        task put(T message);
+    `ifdef VERILATOR_TIMING
+            if (m_bound != 0)
+                wait (m_queue.size() < m_bound);
+            m_queue.push_back(message);
+    `endif
+        endtask
+
+        function int try_put(T message);
+            if (num() < m_bound) begin
+                m_queue.push_back(message);
+                return 1;
+            end
+            return 0;
+        endfunction
+
+        task get(ref T message);
+    `ifdef VERILATOR_TIMING
+            wait (m_queue.size() > 0);
+            message = m_queue.pop_front();
+    `endif
+        endtask
+
+        function int try_get(ref T message);
+            if (num() > 0) begin
+                message = m_queue.pop_front();
+                return 1;
+            end
+            return 0;
+        endfunction
+
+        task peek(ref T message);
+    `ifdef VERILATOR_TIMING
+            wait (m_queue.size() > 0);
+            message = m_queue[0];
+    `endif
+        endtask
+
+        function int try_peek(ref T message);
+            if (num() > 0) begin
+                message = m_queue[0];
+                return 1;
+            end
+            return 0;
+        endfunction
+    endclass
+
+    class semaphore;
+        protected int m_keyCount;
+
+        function new(int keyCount = 0);
+            m_keyCount = keyCount;
+        endfunction
+
+        function void put(int keyCount = 1);
+            m_keyCount += keyCount;
+        endfunction
+
+        task get(int keyCount = 1);
+    `ifdef VERILATOR_TIMING
+            wait (m_keyCount >= keyCount);
+            m_keyCount -= keyCount;
+    `endif
+        endtask
+
+        function int try_get(int keyCount = 1);
+            if (m_keyCount >= keyCount) begin
+                m_keyCount -= keyCount;
+                return 1;
+            end
+            return 0;
+        endfunction
+    endclass
+endpackage
+
+// verilator lint_off IMPORTSTAR
+import std::*;
diff --git a/src/V3AstNodeOther.h b/src/V3AstNodeOther.h
index 6b816d971..a3ae3b246 100644
--- a/src/V3AstNodeOther.h
+++ b/src/V3AstNodeOther.h
@@ -1086,6 +1086,7 @@ class AstNetlist final : public AstNode {
     AstTypeTable* const m_typeTablep;  // Reference to top type table, for faster lookup
     AstConstPool* const m_constPoolp;  // Reference to constant pool, for faster lookup
     AstPackage* m_dollarUnitPkgp = nullptr;  // $unit
+    AstPackage* m_stdPackagep = nullptr;  // SystemVerilog std package
     AstCFunc* m_evalp = nullptr;  // The '_eval' function
     AstCFunc* m_evalNbap = nullptr;  // The '_eval__nba' function
     AstVarScope* m_dpiExportTriggerp = nullptr;  // The DPI export trigger variable
@@ -1119,6 +1120,8 @@ public:
     void dpiExportTriggerp(AstVarScope* varScopep) { m_dpiExportTriggerp = varScopep; }
     AstVar* delaySchedulerp() const { return m_delaySchedulerp; }
     void delaySchedulerp(AstVar* const varScopep) { m_delaySchedulerp = varScopep; }
+    void stdPackagep(AstPackage* const packagep) { m_stdPackagep = packagep; }
+    AstPackage* stdPackagep() const { return m_stdPackagep; }
     AstTopScope* topScopep() const { return m_topScopep; }
     void createTopScope(AstScope* scopep);
     VTimescale timeunit() const { return m_timeunit; }
diff --git a/src/V3Global.cpp b/src/V3Global.cpp
index dd9ec4ac5..20daa8177 100644
--- a/src/V3Global.cpp
+++ b/src/V3Global.cpp
@@ -63,6 +63,13 @@ void V3Global::readFiles() {
                          "Cannot find file containing module: ");
     }
 
+    if (usesStdPackage()) {
+        // Parse the std package
+        parser.parseFile(new FileLine{FileLine::commandLineFilename()},
+                         V3Options::getStdPackagePath(), false,
+                         "Cannot find std.sv containing built-in std:: definitions: ");
+    }
+
     // Read libraries
     // To be compatible with other simulators,
     // this needs to be done after the top file is read
diff --git a/src/V3Global.h b/src/V3Global.h
index 7108f4148..6c8f8dc86 100644
--- a/src/V3Global.h
+++ b/src/V3Global.h
@@ -107,6 +107,7 @@ class V3Global final {
     bool m_dpi = false;  // Need __Dpi include files
     bool m_hasEvents = false;  // Design uses SystemVerilog named events
     bool m_hasClasses = false;  // Design uses SystemVerilog classes
+    bool m_usesStdPackage = false;  // Design uses the std package
     bool m_usesTiming = false;  // Design uses timing constructs
     bool m_hasForceableSignals = false;  // Need to apply V3Force pass
     bool m_hasSCTextSections = false;  // Has `systemc_* sections that need to be emitted
@@ -152,6 +153,8 @@ public:
     void setHasEvents() { m_hasEvents = true; }
     bool hasClasses() const { return m_hasClasses; }
     void setHasClasses() { m_hasClasses = true; }
+    bool usesStdPackage() const { return m_usesStdPackage; }
+    void setUsesStdPackage() { m_usesStdPackage = true; }
     bool usesTiming() const { return m_usesTiming; }
     void setUsesTiming() { m_usesTiming = true; }
     bool hasForceableSignals() const { return m_hasForceableSignals; }
diff --git a/src/V3LinkParse.cpp b/src/V3LinkParse.cpp
index 127d472a3..5d844725c 100644
--- a/src/V3LinkParse.cpp
+++ b/src/V3LinkParse.cpp
@@ -50,6 +50,7 @@ private:
     using ImplTypedefMap = std::map<const std::pair<void*, std::string>, AstTypedef*>;
 
     // STATE
+    AstPackage* const m_stdPackagep;  // SystemVerilog std package
     AstVar* m_varp = nullptr;  // Variable we're under
     ImplTypedefMap m_implTypedef;  // Created typedefs for each <container,name>
     std::unordered_set<FileLine*> m_filelines;  // Filelines that have been seen
@@ -600,6 +601,11 @@ private:
             VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
         }
     }
+    void visit(AstClassOrPackageRef* nodep) override {
+        if (nodep->name() == "std" && !nodep->classOrPackagep()) {
+            nodep->classOrPackagep(m_stdPackagep);
+        }
+    }
 
     void visit(AstNode* nodep) override {
         // Default: Just iterate
@@ -609,7 +615,10 @@ private:
 
 public:
     // CONSTRUCTORS
-    explicit LinkParseVisitor(AstNetlist* rootp) { iterate(rootp); }
+    explicit LinkParseVisitor(AstNetlist* rootp)
+        : m_stdPackagep{rootp->stdPackagep()} {
+        iterate(rootp);
+    }
     ~LinkParseVisitor() override = default;
 };
 
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index a345cd810..4f14b672e 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -706,6 +706,8 @@ string V3Options::getenvVERILATOR_ROOT() {
     return var;
 }
 
+string V3Options::getStdPackagePath() { return getenvVERILATOR_ROOT() + "/include/std.sv"; }
+
 string V3Options::getSupported(const string& var) {
     // If update below, also update V3Options::showVersion()
     if (var == "COROUTINES" && coroutineSupport()) {
diff --git a/src/V3Options.h b/src/V3Options.h
index 1dcb95edf..6fd2e8ac7 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -666,6 +666,7 @@ public:
     static string getenvSYSTEMC_INCLUDE();
     static string getenvSYSTEMC_LIBDIR();
     static string getenvVERILATOR_ROOT();
+    static string getStdPackagePath();
     static string getSupported(const string& var);
     static bool systemCSystemWide();
     static bool systemCFound();  // SystemC installed, or environment points to it
diff --git a/src/V3ParseImp.cpp b/src/V3ParseImp.cpp
index c73b6b64c..e6f1705ca 100644
--- a/src/V3ParseImp.cpp
+++ b/src/V3ParseImp.cpp
@@ -532,14 +532,17 @@ void V3ParseImp::tokenPipelineSym() {
                    && (*(yylval.strp) == "mailbox"  // IEEE-standard class
                        || *(yylval.strp) == "process"  // IEEE-standard class
                        || *(yylval.strp) == "semaphore")) {  // IEEE-standard class
+            v3Global.setUsesStdPackage();
             yylval.scp = nullptr;
             if (token == yaID__LEX) token = yaID__aTYPE;
         } else {  // Not found
             yylval.scp = nullptr;
             if (token == yaID__CC) {
-                // IEEE does require this, but we may relax this as UVM breaks it, so allow bbox
-                // for today
-                if (!v3Global.opt.bboxUnsup()) {
+                if (!m_afterColonColon && *(yylval.strp) == "std") {
+                    v3Global.setUsesStdPackage();
+                } else if (!v3Global.opt.bboxUnsup()) {
+                    // IEEE does require this, but we may relax this as UVM breaks it, so allow
+                    // bbox for today
                     // We'll get a parser error eventually but might not be obvious
                     // is missing package, and this confuses people
                     static int warned = false;
@@ -554,6 +557,7 @@ void V3ParseImp::tokenPipelineSym() {
             }
         }
     }
+    m_afterColonColon = token == yP_COLONCOLON;
     yylval.token = token;
     // effectively returns yylval
 }
diff --git a/src/V3ParseImp.h b/src/V3ParseImp.h
index de7ee0ef7..961e87216 100644
--- a/src/V3ParseImp.h
+++ b/src/V3ParseImp.h
@@ -150,6 +150,7 @@ class V3ParseImp final {
     VOptionBool m_unconnectedDrive;  // Last unconnected drive
 
     int m_lexPrevToken = 0;  // previous parsed token (for lexer)
+    bool m_afterColonColon = false;  // The previous token was '::'
     std::deque<V3ParseBisonYYSType> m_tokensAhead;  // Tokens we parsed ahead of parser
 
     std::deque<string*> m_stringps;  // Created strings for later cleanup
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 3613b6ca3..ab687a457 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -3291,6 +3291,16 @@ private:
         VL_DANGLING(index_exprp);  // May have been edited
         return VN_AS(nodep->pinsp(), Arg)->exprp();
     }
+    void methodCallWarnTiming(AstMethodCall* const nodep, const std::string& className) {
+        if (v3Global.opt.timing().isSetFalse()) {
+            nodep->v3warn(E_NOTIMING,
+                          className << "::" << nodep->name() << "() requires --timing");
+        } else if (!v3Global.opt.timing().isSetTrue()) {
+            nodep->v3warn(E_NEEDTIMINGOPT, "Use --timing or --no-timing to specify how "
+                                               << className << "::" << nodep->name()
+                                               << "() should be handled");
+        }
+    }
     void methodCallClass(AstMethodCall* nodep, AstClassRefDType* adtypep) {
         // No need to width-resolve the class, as it was done when we did the child
         AstClass* const first_classp = adtypep->classp();
@@ -3300,6 +3310,26 @@ private:
         }
         UASSERT_OBJ(first_classp, nodep, "Unlinked");
         for (AstClass* classp = first_classp; classp;) {
+            if (nodep->fileline()->timingOn()) {
+                if (classp->name() == "semaphore"
+                    || VString::startsWith(classp->name(), "mailbox")) {
+                    // Find the package the class is in
+                    AstNode* pkgItemp = classp;
+                    while (pkgItemp->backp() && pkgItemp->backp()->nextp() == pkgItemp) {
+                        pkgItemp = pkgItemp->backp();
+                    }
+                    AstPackage* const packagep = VN_CAST(pkgItemp->backp(), Package);
+                    // Check if it's std
+                    if (packagep && packagep->name() == "std") {
+                        if (classp->name() == "semaphore" && nodep->name() == "get") {
+                            methodCallWarnTiming(nodep, "semaphore");
+                        } else if (nodep->name() == "put" || nodep->name() == "get"
+                                   || nodep->name() == "peek") {
+                            methodCallWarnTiming(nodep, "mailbox");
+                        }
+                    }
+                }
+            }
             if (AstNodeFTask* const ftaskp
                 = VN_CAST(classp->findMember(nodep->name()), NodeFTask)) {
                 userIterate(ftaskp, nullptr);
diff --git a/src/verilog.y b/src/verilog.y
index 61cb9e552..289b4e6fb 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -1162,6 +1162,13 @@ package_declaration:            // ==IEEE: package_declaration
 packageFront<nodeModulep>:
                 yPACKAGE lifetimeE idAny ';'
                         { $$ = new AstPackage{$<fl>3, *$3};
+                          if ($$->name() == "std") {
+                              if ($$->fileline()->filename() != V3Options::getStdPackagePath()) {
+                                  $$->v3error("Redeclaring the 'std' package is not allowed");
+                              } else {
+                                  PARSEP->rootp()->stdPackagep(VN_AS($$, Package));
+                              }
+                          }
                           $$->inLibrary(true);  // packages are always libraries; don't want to make them a "top"
                           $$->lifetime($2);
                           $$->modTrace(GRAMMARP->allTracingOn($$->fileline()));
diff --git a/test_regress/t/t_mailbox.out b/test_regress/t/t_mailbox.out
deleted file mode 100644
index d09756948..000000000
--- a/test_regress/t/t_mailbox.out
+++ /dev/null
@@ -1,6 +0,0 @@
-%Error: t/t_mailbox.v:24:4: Can't find typedef: 'mailbox'
-   24 |    mailbox #(int) m;
-      |    ^~~~~~~
-%Error: Internal Error: t/t_mailbox.v:24:14: ../V3LinkDot.cpp:#: Pin not under instance?
-   24 |    mailbox #(int) m;
-      |              ^~~
diff --git a/test_regress/t/t_mailbox.pl b/test_regress/t/t_mailbox.pl
index 2ad4a887d..d7ae01e91 100755
--- a/test_regress/t/t_mailbox.pl
+++ b/test_regress/t/t_mailbox.pl
@@ -10,14 +10,19 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
-compile(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
-    );
+if (!$Self->have_coroutines) {
+    skip("No coroutine support");
+}
+else {
+    compile(
+        verilator_flags2 => ["--exe --main --timing -Wall"],
+        make_main => 0,
+        );
 
-execute(
-    check_finished => 1,
-    ) if !$Self->{vlt_all};
+    execute(
+        check_finished => 1,
+        );
+}
 
 ok(1);
 1;
diff --git a/test_regress/t/t_mailbox.v b/test_regress/t/t_mailbox.v
index 64e2ba175..e4402f606 100644
--- a/test_regress/t/t_mailbox.v
+++ b/test_regress/t/t_mailbox.v
@@ -20,6 +20,7 @@
  `define MAILBOX_T mailbox
 `endif
 
+// verilator lint_off DECLFILENAME
 module t(/*AUTOARG*/);
    `MAILBOX_T #(int) m;
    int     msg;
diff --git a/test_regress/t/t_mailbox_bad.out b/test_regress/t/t_mailbox_bad.out
index 218a34ad3..3ef286864 100644
--- a/test_regress/t/t_mailbox_bad.out
+++ b/test_regress/t/t_mailbox_bad.out
@@ -1,6 +1,5 @@
-%Error: t/t_mailbox_bad.v:8:4: Can't find typedef: 'mailbox'
-    8 |    mailbox #(int) m;
-      |    ^~~~~~~
-%Error: Internal Error: t/t_mailbox_bad.v:8:14: ../V3LinkDot.cpp:#: Pin not under instance?
-    8 |    mailbox #(int) m;
-      |              ^~~
+%Error: t/t_mailbox_bad.v:12:13: Class method 'bad_method' not found in class 'mailbox__Tz1'
+                               : ... In instance t
+   12 |       if (m.bad_method() != 0) $stop;
+      |             ^~~~~~~~~~
+%Error: Exiting due to
diff --git a/test_regress/t/t_mailbox_std.out b/test_regress/t/t_mailbox_std.out
deleted file mode 100644
index d09756948..000000000
--- a/test_regress/t/t_mailbox_std.out
+++ /dev/null
@@ -1,6 +0,0 @@
-%Error: t/t_mailbox.v:24:4: Can't find typedef: 'mailbox'
-   24 |    mailbox #(int) m;
-      |    ^~~~~~~
-%Error: Internal Error: t/t_mailbox.v:24:14: ../V3LinkDot.cpp:#: Pin not under instance?
-   24 |    mailbox #(int) m;
-      |              ^~~
diff --git a/test_regress/t/t_mailbox_std.pl b/test_regress/t/t_mailbox_std.pl
index 3b640c6e1..54f95ce97 100755
--- a/test_regress/t/t_mailbox_std.pl
+++ b/test_regress/t/t_mailbox_std.pl
@@ -10,17 +10,21 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
-top_filename("t/t_mailbox.v");
+if (!$Self->have_coroutines) {
+    skip("No coroutine support");
+}
+else {
+    top_filename("t/t_mailbox.v");
 
-compile(
-    v_flags2 => ["+define+T_MAILBOX+std::mailbox"],
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
-    );
+    compile(
+        verilator_flags2 => ["--exe --main --timing -Wall -DMAILBOX_T=std::mailbox"],
+        make_main => 0,
+        );
 
-execute(
-    check_finished => 1,
-    ) if !$Self->{vlt_all};
+    execute(
+        check_finished => 1,
+        );
+}
 
 ok(1);
 1;
diff --git a/test_regress/t/t_notiming.out b/test_regress/t/t_notiming.out
index b625df546..e12212acd 100644
--- a/test_regress/t/t_notiming.out
+++ b/test_regress/t/t_notiming.out
@@ -30,4 +30,20 @@
                                       : ... In instance t
    27 |    initial #2 $stop;  
       |            ^
+%Error-NOTIMING: t/t_notiming.v:33:10: mailbox::put() requires --timing
+                                     : ... In instance t
+   33 |        m.put(i);
+      |          ^~~
+%Error-NOTIMING: t/t_notiming.v:34:10: mailbox::get() requires --timing
+                                     : ... In instance t
+   34 |        m.get(i);
+      |          ^~~
+%Error-NOTIMING: t/t_notiming.v:35:10: mailbox::peek() requires --timing
+                                     : ... In instance t
+   35 |        m.peek(i);
+      |          ^~~~
+%Error-NOTIMING: t/t_notiming.v:36:10: semaphore::get() requires --timing
+                                     : ... In instance t
+   36 |        s.get();
+      |          ^~~
 %Error: Exiting due to
diff --git a/test_regress/t/t_notiming.v b/test_regress/t/t_notiming.v
index 649888e1f..ae163d23c 100644
--- a/test_regress/t/t_notiming.v
+++ b/test_regress/t/t_notiming.v
@@ -25,6 +25,16 @@ module t;
 
    initial #1 ->e;
    initial #2 $stop; // timeout
+
+   mailbox#(int) m = new;
+   semaphore s = new;
+   initial begin
+       int i;
+       m.put(i);
+       m.get(i);
+       m.peek(i);
+       s.get();
+   end
 endmodule
 
 `ifdef VERILATOR_TIMING
diff --git a/test_regress/t/t_semaphore.out b/test_regress/t/t_semaphore.out
deleted file mode 100644
index 95ce89973..000000000
--- a/test_regress/t/t_semaphore.out
+++ /dev/null
@@ -1,7 +0,0 @@
-%Error: t/t_semaphore.v:21:4: Can't find typedef: 'semaphore'
-   21 |    semaphore s;
-      |    ^~~~~~~~~
-%Error: t/t_semaphore.v:22:4: Can't find typedef: 'semaphore'
-   22 |    semaphore s2;
-      |    ^~~~~~~~~
-%Error: Exiting due to
diff --git a/test_regress/t/t_semaphore.pl b/test_regress/t/t_semaphore.pl
index 2ad4a887d..d7ae01e91 100755
--- a/test_regress/t/t_semaphore.pl
+++ b/test_regress/t/t_semaphore.pl
@@ -10,14 +10,19 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
-compile(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
-    );
+if (!$Self->have_coroutines) {
+    skip("No coroutine support");
+}
+else {
+    compile(
+        verilator_flags2 => ["--exe --main --timing -Wall"],
+        make_main => 0,
+        );
 
-execute(
-    check_finished => 1,
-    ) if !$Self->{vlt_all};
+    execute(
+        check_finished => 1,
+        );
+}
 
 ok(1);
 1;
diff --git a/test_regress/t/t_semaphore.v b/test_regress/t/t_semaphore.v
index 500fac7e8..6635cff9d 100644
--- a/test_regress/t/t_semaphore.v
+++ b/test_regress/t/t_semaphore.v
@@ -16,11 +16,11 @@
  `define SEMAPHORE_T semaphore
 `endif
 
+// verilator lint_off DECLFILENAME
 module t(/*AUTOARG*/);
    // From UVM:
    `SEMAPHORE_T s;
    `SEMAPHORE_T s2;
-   int       msg;
 
    initial begin
       s = new(1);
diff --git a/test_regress/t/t_semaphore_bad.out b/test_regress/t/t_semaphore_bad.out
index c07616459..2fc1c33cb 100644
--- a/test_regress/t/t_semaphore_bad.out
+++ b/test_regress/t/t_semaphore_bad.out
@@ -1,4 +1,5 @@
-%Error: t/t_semaphore_bad.v:8:4: Can't find typedef: 'semaphore'
-    8 |    semaphore s;
-      |    ^~~~~~~~~
+%Error: t/t_semaphore_bad.v:12:13: Class method 'bad_method' not found in class 'semaphore'
+                                 : ... In instance t
+   12 |       if (s.bad_method() != 0) $stop;
+      |             ^~~~~~~~~~
 %Error: Exiting due to
diff --git a/test_regress/t/t_semaphore_std.out b/test_regress/t/t_semaphore_std.out
deleted file mode 100644
index 95ce89973..000000000
--- a/test_regress/t/t_semaphore_std.out
+++ /dev/null
@@ -1,7 +0,0 @@
-%Error: t/t_semaphore.v:21:4: Can't find typedef: 'semaphore'
-   21 |    semaphore s;
-      |    ^~~~~~~~~
-%Error: t/t_semaphore.v:22:4: Can't find typedef: 'semaphore'
-   22 |    semaphore s2;
-      |    ^~~~~~~~~
-%Error: Exiting due to
diff --git a/test_regress/t/t_semaphore_std.pl b/test_regress/t/t_semaphore_std.pl
index ece82f871..7fcb5b404 100755
--- a/test_regress/t/t_semaphore_std.pl
+++ b/test_regress/t/t_semaphore_std.pl
@@ -10,17 +10,21 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(simulator => 1);
 
-top_filename("t/t_semaphore.v");
+if (!$Self->have_coroutines) {
+    skip("No coroutine support");
+}
+else {
+    top_filename("t/t_semaphore.v");
 
-compile(
-    v_flags2 => ["+define+T_SEMAPHORE+std::semaphore"],
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
-    );
+    compile(
+        verilator_flags2 => ["--exe --main --timing -Wall -DSEMAPHORE_T=std::semaphore"],
+        make_main => 0,
+        );
 
-execute(
-    check_finished => 1,
-    ) if !$Self->{vlt_all};
+    execute(
+        check_finished => 1,
+        );
+}
 
 ok(1);
 1;
diff --git a/test_regress/t/t_std_identifier.out b/test_regress/t/t_std_identifier.out
new file mode 100644
index 000000000..1b970e684
--- /dev/null
+++ b/test_regress/t/t_std_identifier.out
@@ -0,0 +1,5 @@
+%Error-PKGNODECL: t/t_std_identifier.v:16:20: Package/class 'std' not found, and needs to be predeclared (IEEE 1800-2017 26.3)
+   16 |     int baz = foo::std::bar;
+      |                    ^~~
+                  ... For error description see https://verilator.org/warn/PKGNODECL?v=latest
+%Error: Exiting due to
diff --git a/test_regress/t/t_semaphore_parse.pl b/test_regress/t/t_std_identifier.pl
similarity index 65%
rename from test_regress/t/t_semaphore_parse.pl
rename to test_regress/t/t_std_identifier.pl
index 8149e4600..3e2acea9f 100755
--- a/test_regress/t/t_semaphore_parse.pl
+++ b/test_regress/t/t_std_identifier.pl
@@ -2,18 +2,21 @@
 if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
 # DESCRIPTION: Verilator: Verilog Test driver/expect definition
 #
-# Copyright 2003 by Wilson Snyder. This program is free software; you
+# Copyright 2022 by Antmicro Ltd. 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(vlt => 1);
-
-top_filename("t_semaphore.v");
+scenarios(linter => 1);
 
 lint(
-    verilator_flags2 => ["--debug-exit-uvm"],
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+lint(
+    verilator_flags2 => ["-DTEST_DECLARE_STD"],
     );
 
 ok(1);
diff --git a/test_regress/t/t_std_identifier.v b/test_regress/t/t_std_identifier.v
new file mode 100644
index 000000000..882fb5658
--- /dev/null
+++ b/test_regress/t/t_std_identifier.v
@@ -0,0 +1,17 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2022 by Antmicro Ltd.
+// SPDX-License-Identifier: CC0-1.0
+
+package foo;
+`ifdef TEST_DECLARE_STD
+    class std;
+        static int bar;
+    endclass
+`endif
+endpackage
+
+module t;
+    int baz = foo::std::bar;
+endmodule
diff --git a/test_regress/t/t_std_pkg_bad.out b/test_regress/t/t_std_pkg_bad.out
new file mode 100644
index 000000000..54a735e56
--- /dev/null
+++ b/test_regress/t/t_std_pkg_bad.out
@@ -0,0 +1,4 @@
+%Error: t/t_std_pkg_bad.v:7:9: Redeclaring the 'std' package is not allowed
+    7 | package std;
+      |         ^~~
+%Error: Exiting due to
diff --git a/test_regress/t/t_mailbox_parse.pl b/test_regress/t/t_std_pkg_bad.pl
similarity index 71%
rename from test_regress/t/t_mailbox_parse.pl
rename to test_regress/t/t_std_pkg_bad.pl
index 6074d4d9a..19ba90d40 100755
--- a/test_regress/t/t_mailbox_parse.pl
+++ b/test_regress/t/t_std_pkg_bad.pl
@@ -2,18 +2,17 @@
 if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
 # DESCRIPTION: Verilator: Verilog Test driver/expect definition
 #
-# Copyright 2003 by Wilson Snyder. This program is free software; you
+# Copyright 2022 by Antmicro Ltd. 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(vlt => 1);
-
-top_filename("t_mailbox.v");
+scenarios(linter => 1);
 
 lint(
-    verilator_flags2 => ["--debug-exit-uvm"],
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
     );
 
 ok(1);
diff --git a/test_regress/t/t_std_pkg_bad.v b/test_regress/t/t_std_pkg_bad.v
new file mode 100644
index 000000000..c1969368e
--- /dev/null
+++ b/test_regress/t/t_std_pkg_bad.v
@@ -0,0 +1,11 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2022 by Antmicro Ltd.
+// SPDX-License-Identifier: CC0-1.0
+
+package std;
+endpackage
+
+module t;
+endmodule
diff --git a/test_regress/t/t_timing_unset1.out b/test_regress/t/t_timing_unset1.out
index c6bcbb64a..eb8c53eb8 100644
--- a/test_regress/t/t_timing_unset1.out
+++ b/test_regress/t/t_timing_unset1.out
@@ -31,4 +31,20 @@
                                           : ... In instance t
    27 |    initial #2 $stop;  
       |            ^
+%Error-NEEDTIMINGOPT: t/t_notiming.v:33:10: Use --timing or --no-timing to specify how mailbox::put() should be handled
+                                          : ... In instance t
+   33 |        m.put(i);
+      |          ^~~
+%Error-NEEDTIMINGOPT: t/t_notiming.v:34:10: Use --timing or --no-timing to specify how mailbox::get() should be handled
+                                          : ... In instance t
+   34 |        m.get(i);
+      |          ^~~
+%Error-NEEDTIMINGOPT: t/t_notiming.v:35:10: Use --timing or --no-timing to specify how mailbox::peek() should be handled
+                                          : ... In instance t
+   35 |        m.peek(i);
+      |          ^~~~
+%Error-NEEDTIMINGOPT: t/t_notiming.v:36:10: Use --timing or --no-timing to specify how semaphore::get() should be handled
+                                          : ... In instance t
+   36 |        s.get();
+      |          ^~~
 %Error: Exiting due to