diff --git a/src/V3LinkDot.cpp b/src/V3LinkDot.cpp
index 8be28c54e..89abc2c2a 100644
--- a/src/V3LinkDot.cpp
+++ b/src/V3LinkDot.cpp
@@ -3255,6 +3255,10 @@ private:
                                        " (IEEE 1800-2017 8.13)");
                     }
                     if (cextp->childDTypep() || cextp->dtypep()) continue;  // Already converted
+                    if (VN_IS(cextp->classOrPkgsp(), Dot)) {
+                        itemp->v3warn(E_UNSUPPORTED, "Unsupported: Hierarchical class references");
+                        continue;
+                    }
                     AstClassOrPackageRef* const cpackagerefp
                         = VN_CAST(cextp->classOrPkgsp(), ClassOrPackageRef);
                     if (VL_UNCOVERABLE(!cpackagerefp)) {
diff --git a/src/verilog.y b/src/verilog.y
index 677d9d2b4..fba31aa97 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -6643,11 +6643,6 @@ classExtendsOne<classExtendsp>:         // IEEE: part of class_declaration
                 class_typeExtImpList
                         { $$ = new AstClassExtends{$1->fileline(), $1, GRAMMARP->m_inImplements};
                           $<scp>$ = $<scp>1; }
-        //
-        |       class_typeExtImpList '(' list_of_argumentsE ')'
-                        { $$ = new AstClassExtends{$1->fileline(), $1, GRAMMARP->m_inImplements};
-                          $<scp>$ = $<scp>1;
-                          if ($3) BBUNSUP($3, "Unsupported: extends with parameters"); }
         ;
 
 classImplementsE<classExtendsp>:        // IEEE: part of class_declaration
@@ -6667,18 +6662,16 @@ classImplementsList<classExtendsp>:     // IEEE: part of class_declaration
                        { $$ = addNextNull($1, $3); $<scp>$ = $<scp>3; }
         ;
 
-class_typeExtImpList<nodep>:    // IEEE: class_type: "[package_scope] id [ parameter_value_assignment ]"
+class_typeExtImpList<nodeExprp>:  // IEEE: class_type: "[package_scope] id [ parameter_value_assignment ]"
         //                      // but allow yaID__aTYPE for extends/implements
         //                      // If you follow the rules down, class_type is really a list via ps_class_identifier
                 class_typeExtImpOne                     { $$ = $1; $<scp>$ = $<scp>1; }
         |       class_typeExtImpList yP_COLONCOLON class_typeExtImpOne
-                        { $$ = $3; $<scp>$ = $<scp>1;
-                          // Cannot just add as next() as that breaks implements lists
-                          //UNSUP $$ = new AstDot{$<fl>1, true, $1, $3};
-                          BBUNSUP($2, "Unsupported: Hierarchical class references"); }
+                        { $$ = new AstDot{$<fl>1, true, $1, $3};
+                          $<scp>$ = $<scp>3; }
         ;
 
-class_typeExtImpOne<nodep>:     // part of IEEE: class_type, where we either get a package_scope component or class
+class_typeExtImpOne<nodeExprp>:  // part of IEEE: class_type, where we either get a package_scope component or class
         //                      // If you follow the rules down, class_type is really a list via ps_class_identifier
         //                      // Not listed in IEEE, but see bug627 any parameter type maybe a class
         //                      // If idAny below is a class, parameter_value is legal
@@ -6686,6 +6679,11 @@ class_typeExtImpOne<nodep>:     // part of IEEE: class_type, where we either get
         //                      // If idAny below is otherwise, not legal
                 idAny
         /*mid*/         { /* no nextId as not refing it above this*/ }
+        /*cont*/    parameter_value_assignmentE
+                        { $$ = new AstClassOrPackageRef{$<fl>1, *$1, $<scp>1, $3};
+                          $<scp>$ = $<scp>1; }
+        |       idCC
+        /*mid*/         { /* no nextId as not refing it above this*/ }
         /*cont*/    parameter_value_assignmentE
                         { $$ = new AstClassOrPackageRef{$<fl>1, *$1, $<scp>1, $3};
                           $<scp>$ = $<scp>1; }
diff --git a/test_regress/t/t_class_extends2.out b/test_regress/t/t_class_extends2.out
new file mode 100644
index 000000000..9b587f905
--- /dev/null
+++ b/test_regress/t/t_class_extends2.out
@@ -0,0 +1,5 @@
+%Error-UNSUPPORTED: t/t_class_extends2.v:18:19: Unsupported: Hierarchical class references
+   18 | class Ext extends Pkg::Base0;
+      |                   ^~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error: Exiting due to
diff --git a/test_regress/t/t_class_extends2.pl b/test_regress/t/t_class_extends2.pl
new file mode 100755
index 000000000..8a9b721f2
--- /dev/null
+++ b/test_regress/t/t_class_extends2.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2020 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(linter => 1);
+
+lint(
+    fails => $Self->{vlt},
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_class_extends2.v b/test_regress/t/t_class_extends2.v
new file mode 100644
index 000000000..8c30f0c6b
--- /dev/null
+++ b/test_regress/t/t_class_extends2.v
@@ -0,0 +1,47 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2020 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+package Pkg;
+class Base0;
+   int baseonly;
+   int baseover;
+
+   function void b_set_bo(int v); baseover = v; endfunction
+   function int b_get_bo(); return baseover; endfunction
+   function int get_bo(); return baseover; endfunction
+endclass
+endpackage
+
+class Ext extends Pkg::Base0;
+   int baseover;
+   int extonly;
+
+   function void e_set_bo(int v); baseover = v; endfunction
+   function int e_get_bo(); return baseover; endfunction
+   function int get_bo(); return baseover; endfunction
+endclass
+
+module t (/*AUTOARG*/);
+   initial begin
+      Ext c;
+      c = new;
+      c.baseonly = 10;
+      c.baseover = 20;
+      c.extonly = 30;
+      if (c.baseonly != 10) $stop;
+      if (c.baseover != 20) $stop;
+      if (c.extonly != 30) $stop;
+
+      c.b_set_bo(100);
+      c.e_set_bo(200);
+      if (c.b_get_bo() != 100) $stop;
+      if (c.e_get_bo() != 200) $stop;
+      if (c.get_bo() != 200) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule
diff --git a/test_regress/t/t_class_extends_colon.out b/test_regress/t/t_class_extends_colon.out
new file mode 100644
index 000000000..ae67bbf79
--- /dev/null
+++ b/test_regress/t/t_class_extends_colon.out
@@ -0,0 +1,5 @@
+%Error-UNSUPPORTED: t/t_class_extends_colon.v:20:21: Unsupported: Hierarchical class references
+   20 | class Cls12 extends Pkg::Icls1;
+      |                     ^~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error: Exiting due to
diff --git a/test_regress/t/t_class_extends_colon.pl b/test_regress/t/t_class_extends_colon.pl
new file mode 100755
index 000000000..8a9b721f2
--- /dev/null
+++ b/test_regress/t/t_class_extends_colon.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2020 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(linter => 1);
+
+lint(
+    fails => $Self->{vlt},
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_class_extends_colon.v b/test_regress/t/t_class_extends_colon.v
new file mode 100644
index 000000000..cf4fea9a0
--- /dev/null
+++ b/test_regress/t/t_class_extends_colon.v
@@ -0,0 +1,35 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+interface class Icempty;
+endclass : Icempty
+
+package Pkg;
+class Icls1 #(parameter PARAM = 12);
+   localparam LP1 = 1;
+   function int getParam();
+      return PARAM;
+   endfunction
+endclass
+
+endpackage
+
+class Cls12 extends Pkg::Icls1;
+endclass
+
+module t(/*AUTOARG*/);
+
+   Cls12 cp12;
+
+   initial begin
+      cp12 = new;
+      if (cp12.getParam() != 12) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule