diff --git a/Changes b/Changes
index 0b4e62124..a16337032 100644
--- a/Changes
+++ b/Changes
@@ -13,6 +13,8 @@ Verilator 5.007 devel
 
 **Minor:**
 
+* Support unpacked unions.
+
 
 Verilator 5.006 2022-01-22
 ==========================
diff --git a/src/V3AstNodeDType.h b/src/V3AstNodeDType.h
index a50a88006..d64e81ab0 100644
--- a/src/V3AstNodeDType.h
+++ b/src/V3AstNodeDType.h
@@ -200,6 +200,7 @@ private:
     using MemberNameMap = std::map<const std::string, AstMemberDType*>;
     // MEMBERS
     string m_name;  // Name from upper typedef, if any
+    AstNodeModule* m_classOrPackagep = nullptr;  // Package hierarchy
     MemberNameMap m_members;
     const int m_uniqueNum;
     bool m_packed;
@@ -255,6 +256,8 @@ public:
     static int lo() { return 0; }
     int hi() const { return dtypep()->width() - 1; }  // Packed classes look like arrays
     VNumRange declRange() const { return VNumRange{hi(), lo()}; }
+    AstNodeModule* classOrPackagep() const { return m_classOrPackagep; }
+    void classOrPackagep(AstNodeModule* classpackagep) { m_classOrPackagep = classpackagep; }
 };
 
 // === Concrete node types =====================================================
@@ -1319,15 +1322,12 @@ public:
 
 // === AstNodeUOrStructDType ===
 class AstStructDType final : public AstNodeUOrStructDType {
-    AstNodeModule* m_classOrPackagep = nullptr;  // Package hierarchy
 public:
     // VSigning below is mispurposed to indicate if packed or not
     AstStructDType(FileLine* fl, VSigning numericUnpack)
         : ASTGEN_SUPER_StructDType(fl, numericUnpack) {}
     ASTGEN_MEMBERS_AstStructDType;
     string verilogKwd() const override { return "struct"; }
-    AstNodeModule* classOrPackagep() const { return m_classOrPackagep; }
-    void classOrPackagep(AstNodeModule* classpackagep) { m_classOrPackagep = classpackagep; }
 };
 class AstUnionDType final : public AstNodeUOrStructDType {
 public:
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index 7c69d1007..d3ed29858 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -737,8 +737,8 @@ AstNodeDType::CTypeRecursed AstNodeDType::cTypeRecurse(bool compound) const {
         info.m_type = "VlUnpacked<" + sub.m_type;
         info.m_type += ", " + cvtToStr(adtypep->declRange().elements());
         info.m_type += ">";
-    } else if (VN_IS(dtypep, StructDType) && !VN_AS(dtypep, StructDType)->packed()) {
-        const auto* const sdtypep = VN_AS(dtypep, StructDType);
+    } else if (VN_IS(dtypep, NodeUOrStructDType) && !VN_AS(dtypep, NodeUOrStructDType)->packed()) {
+        const auto* const sdtypep = VN_AS(dtypep, NodeUOrStructDType);
         info.m_type = EmitCBaseVisitor::prefixNameProtect(sdtypep);
     } else if (const AstBasicDType* const bdtypep = dtypep->basicp()) {
         // We don't print msb()/lsb() as multidim packed would require recursion,
diff --git a/src/V3CUse.cpp b/src/V3CUse.cpp
index 85a03b697..9085ba8d9 100644
--- a/src/V3CUse.cpp
+++ b/src/V3CUse.cpp
@@ -75,7 +75,7 @@ class CUseVisitor final : public VNVisitor {
         if (nodep->virtRefDType2p()) iterate(nodep->virtRefDType2p());
 
         // Add a CUse for every struct that requires a declaration
-        AstStructDType* const stypep = VN_CAST(nodep->skipRefp(), StructDType);
+        AstNodeUOrStructDType* const stypep = VN_CAST(nodep->skipRefp(), NodeUOrStructDType);
         if (stypep && stypep->classOrPackagep()) {
             addNewUse(nodep, VUseType::INT_INCLUDE, stypep->classOrPackagep()->name());
             iterateChildren(stypep);
diff --git a/src/V3Class.cpp b/src/V3Class.cpp
index f5e65b2a0..755c94663 100644
--- a/src/V3Class.cpp
+++ b/src/V3Class.cpp
@@ -171,24 +171,25 @@ private:
         }
     }
 
-    void setStructModulep(AstStructDType* const dtypep) {
+    void setStructModulep(AstNodeUOrStructDType* const dtypep) {
         // Give it a pointer to its package and a final name
         dtypep->classOrPackagep(m_modp);
-        dtypep->name(dtypep->name() + "__struct" + cvtToStr(dtypep->uniqueNum()));
+        dtypep->name(dtypep->name() + (VN_IS(dtypep, UnionDType) ? "__union" : "__struct")
+                     + cvtToStr(dtypep->uniqueNum()));
 
         for (const AstMemberDType* itemp = dtypep->membersp(); itemp;
              itemp = VN_AS(itemp->nextp(), MemberDType)) {
-            AstStructDType* const subp = VN_CAST(itemp->skipRefp(), StructDType);
+            AstNodeUOrStructDType* const subp = VN_CAST(itemp->skipRefp(), NodeUOrStructDType);
             // Recurse only into anonymous unpacked structs inside this definition,
             // other unpacked structs will be reached from another typedefs
-            if (subp && !subp->packed() && subp->name().empty()) { setStructModulep(subp); }
+            if (subp && !subp->packed() && subp->name().empty()) setStructModulep(subp);
         }
     }
     void visit(AstTypedef* nodep) override {
         if (nodep->user1SetOnce()) return;
         iterateChildren(nodep);
 
-        AstStructDType* const dtypep = VN_CAST(nodep->dtypep(), StructDType);
+        AstNodeUOrStructDType* const dtypep = VN_CAST(nodep->dtypep(), NodeUOrStructDType);
         if (dtypep && !dtypep->packed()) {
             dtypep->name(nodep->name());
             setStructModulep(dtypep);
diff --git a/src/V3Clean.cpp b/src/V3Clean.cpp
index bcd392abd..1ac678acc 100644
--- a/src/V3Clean.cpp
+++ b/src/V3Clean.cpp
@@ -97,9 +97,9 @@ private:
                 || VN_IS(nodep->dtypep()->skipRefp(), UnpackArrayDType)
                 || VN_IS(nodep->dtypep()->skipRefp(), VoidDType)) {
             } else {
-                const AstStructDType* const dtypep
-                    = VN_CAST(nodep->dtypep()->skipRefp(), StructDType);
-                if (!dtypep || dtypep->packed()) { setCppWidth(nodep); }
+                const AstNodeUOrStructDType* const dtypep
+                    = VN_CAST(nodep->dtypep()->skipRefp(), NodeUOrStructDType);
+                if (!dtypep || dtypep->packed()) setCppWidth(nodep);
             }
         }
     }
diff --git a/src/V3Common.cpp b/src/V3Common.cpp
index 5e589d4d7..68999f3fd 100644
--- a/src/V3Common.cpp
+++ b/src/V3Common.cpp
@@ -61,7 +61,7 @@ static void makeVlToString(AstIface* nodep) {
     funcp->addStmtsp(new AstCReturn{nodep->fileline(), exprp});
     nodep->addStmtsp(funcp);
 }
-static void makeVlToString(AstStructDType* nodep) {
+static void makeVlToString(AstNodeUOrStructDType* nodep) {
     AstNodeModule* const modp = nodep->classOrPackagep();
     AstCFunc* const funcp
         = new AstCFunc{nodep->fileline(), "VL_TO_STRING", nullptr, "std::string"};
@@ -168,7 +168,7 @@ void V3Common::commonAll() {
     }
     for (AstNode* nodep = v3Global.rootp()->typeTablep()->typesp(); nodep;
          nodep = nodep->nextp()) {
-        if (AstStructDType* const dtypep = VN_CAST(nodep, StructDType)) {
+        if (AstNodeUOrStructDType* const dtypep = VN_CAST(nodep, NodeUOrStructDType)) {
             if (!dtypep->packed()) makeVlToString(dtypep);
         }
     }
diff --git a/src/V3Dead.cpp b/src/V3Dead.cpp
index 2b45be47f..5faad31e1 100644
--- a/src/V3Dead.cpp
+++ b/src/V3Dead.cpp
@@ -324,7 +324,7 @@ private:
         }
     }
     bool shouldDeleteTypedef(AstTypedef* typedefp) {
-        if (auto* structp = VN_CAST(typedefp->subDTypep(), StructDType)) {
+        if (auto* const structp = VN_CAST(typedefp->subDTypep(), NodeUOrStructDType)) {
             if (structp->user1() && !structp->packed()) return false;
         }
         return m_elimCells && !typedefp->attrPublic();
diff --git a/src/V3EmitCFunc.cpp b/src/V3EmitCFunc.cpp
index 0184a8b88..2922d6706 100644
--- a/src/V3EmitCFunc.cpp
+++ b/src/V3EmitCFunc.cpp
@@ -673,8 +673,8 @@ string EmitCFunc::emitVarResetRecurse(const AstVar* varp, const string& varNameP
                                                  depth + 1, suffix + "[" + ivar + "]");
         const string post = "}\n";
         return below.empty() ? "" : pre + below + post;
-    } else if (VN_IS(dtypep, StructDType) && !VN_AS(dtypep, StructDType)->packed()) {
-        const auto* const sdtypep = VN_AS(dtypep, StructDType);
+    } else if (VN_IS(dtypep, NodeUOrStructDType) && !VN_AS(dtypep, NodeUOrStructDType)->packed()) {
+        const auto* const sdtypep = VN_AS(dtypep, NodeUOrStructDType);
         string literal;
         for (const AstMemberDType* itemp = sdtypep->membersp(); itemp;
              itemp = VN_AS(itemp->nextp(), MemberDType)) {
diff --git a/src/V3EmitCHeaders.cpp b/src/V3EmitCHeaders.cpp
index 744e13baf..3b0ef1abe 100644
--- a/src/V3EmitCHeaders.cpp
+++ b/src/V3EmitCHeaders.cpp
@@ -208,13 +208,13 @@ class EmitCHeader final : public EmitCConstInit {
             }
         }
     }
-    void emitStructDecl(const AstNodeModule* modp, AstStructDType* sdtypep,
-                        std::set<AstStructDType*>& emitted) {
+    void emitStructDecl(const AstNodeModule* modp, AstNodeUOrStructDType* sdtypep,
+                        std::set<AstNodeUOrStructDType*>& emitted) {
         if (emitted.count(sdtypep) > 0) return;
         emitted.insert(sdtypep);
         for (const AstMemberDType* itemp = sdtypep->membersp(); itemp;
              itemp = VN_AS(itemp->nextp(), MemberDType)) {
-            AstStructDType* subp = VN_CAST(itemp->skipRefp(), StructDType);
+            AstNodeUOrStructDType* subp = VN_CAST(itemp->skipRefp(), NodeUOrStructDType);
             if (subp && !subp->packed()) {
                 // Recurse if it belongs to the current module
                 if (subp->classOrPackagep() == modp) {
@@ -223,7 +223,8 @@ class EmitCHeader final : public EmitCConstInit {
                 }
             }
         }
-        puts("struct " + EmitCBaseVisitor::prefixNameProtect(sdtypep) + " {\n");
+        puts(sdtypep->verilogKwd());  // "struct"/"union"
+        puts(" " + EmitCBaseVisitor::prefixNameProtect(sdtypep) + " {\n");
         for (const AstMemberDType* itemp = sdtypep->membersp(); itemp;
              itemp = VN_AS(itemp->nextp(), MemberDType)) {
             puts(itemp->dtypep()->cType(itemp->nameProtect(), false, false));
@@ -234,12 +235,12 @@ class EmitCHeader final : public EmitCConstInit {
     void emitStructs(const AstNodeModule* modp) {
         bool first = true;
         // Track structs that've been emitted already
-        std::set<AstStructDType*> emitted;
+        std::set<AstNodeUOrStructDType*> emitted;
         for (const AstNode* nodep = modp->stmtsp(); nodep; nodep = nodep->nextp()) {
             const AstTypedef* const tdefp = VN_CAST(nodep, Typedef);
             if (!tdefp) continue;
-            AstStructDType* const sdtypep
-                = VN_CAST(tdefp->dtypep()->skipRefToEnump(), StructDType);
+            AstNodeUOrStructDType* const sdtypep
+                = VN_CAST(tdefp->dtypep()->skipRefToEnump(), NodeUOrStructDType);
             if (!sdtypep) continue;
             if (sdtypep->packed()) continue;
             decorateFirst(first, "\n// UNPACKED STRUCT TYPES\n");
diff --git a/src/V3EmitCImp.cpp b/src/V3EmitCImp.cpp
index 16e24ac64..efd8d6c22 100644
--- a/src/V3EmitCImp.cpp
+++ b/src/V3EmitCImp.cpp
@@ -50,7 +50,8 @@ class EmitCGatherDependencies final : VNVisitor {
         if (const AstClassRefDType* const dtypep = VN_CAST(nodep, ClassRefDType)) {
             m_dependencies.insert(
                 EmitCBaseVisitor::prefixNameProtect(dtypep->classp()->classOrPackagep()));
-        } else if (const AstStructDType* const dtypep = VN_CAST(nodep, StructDType)) {
+        } else if (const AstNodeUOrStructDType* const dtypep
+                   = VN_CAST(nodep, NodeUOrStructDType)) {
             if (!dtypep->packed()) {
                 m_dependencies.insert(
                     EmitCBaseVisitor::prefixNameProtect(dtypep->classOrPackagep()));
diff --git a/src/V3Simulate.h b/src/V3Simulate.h
index b77d89840..116596dad 100644
--- a/src/V3Simulate.h
+++ b/src/V3Simulate.h
@@ -122,7 +122,7 @@ private:
         if (AstRefDType* const refdtypep = VN_CAST(dtypep, RefDType)) {  //
             dtypep = refdtypep->skipRefp();
         }
-        if (AstStructDType* const stp = VN_CAST(dtypep, StructDType)) {
+        if (AstNodeUOrStructDType* const stp = VN_CAST(dtypep, NodeUOrStructDType)) {
             if (stp->packed()) {
                 std::ostringstream out;
                 out << "'{";
@@ -418,7 +418,7 @@ private:
         if (!VN_IS(nodep->varp()->dtypeSkipRefp(), BasicDType)
             && !VN_IS(nodep->varp()->dtypeSkipRefp(), PackArrayDType)
             && !VN_IS(nodep->varp()->dtypeSkipRefp(), UnpackArrayDType)
-            && !VN_IS(nodep->varp()->dtypeSkipRefp(), StructDType))
+            && !VN_IS(nodep->varp()->dtypeSkipRefp(), NodeUOrStructDType))
             clearOptimizable(nodep, "Array references/not basic");
         if (nodep->access().isWriteOrRW()) {
             if (m_inDlyAssign) {
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 32899dce3..52cec557d 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -2478,13 +2478,7 @@ private:
         if (nodep->didWidthAndSet()) return;  // This node is a dtype & not both PRELIMed+FINALed
         UINFO(5, "   NODECLASS " << nodep << endl);
         // if (debug() >= 9) nodep->dumpTree("-  class-in: ");
-        if (!nodep->packed()) {
-            if (VN_IS(nodep, UnionDType)) {
-                nodep->v3warn(UNPACKED, "Unsupported: Unpacked union");
-            } else if (v3Global.opt.structsPacked()) {
-                nodep->packed(true);
-            }
-        }
+        if (!nodep->packed() && v3Global.opt.structsPacked()) { nodep->packed(true); }
         userIterateChildren(nodep, nullptr);  // First size all members
         nodep->repairMemberCache();
         nodep->dtypep(nodep);
@@ -4594,7 +4588,7 @@ private:
                                || VN_IS(dtypep, DynArrayDType)  //
                                || VN_IS(dtypep, UnpackArrayDType)  //
                                || VN_IS(dtypep, QueueDType)
-                               || (VN_IS(dtypep, StructDType)
+                               || (VN_IS(dtypep, NodeUOrStructDType)
                                    && !VN_AS(dtypep, StructDType)->packed())) {
                         added = true;
                         newFormat += "%@";
diff --git a/test_regress/t/t_union_unpacked_bad.pl b/test_regress/t/t_union_unpacked.pl
similarity index 70%
rename from test_regress/t/t_union_unpacked_bad.pl
rename to test_regress/t/t_union_unpacked.pl
index 59ba0d6c6..859050d63 100755
--- a/test_regress/t/t_union_unpacked_bad.pl
+++ b/test_regress/t/t_union_unpacked.pl
@@ -2,17 +2,19 @@
 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 2023 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);
+scenarios(simulator => 1);
 
-lint(
-    fails => $Self->{vlt_all},
-    expect_filename => $Self->{golden_filename},
+compile(
+    );
+
+execute(
+    check_finished => 1,
     );
 
 ok(1);
diff --git a/test_regress/t/t_union_unpacked_bad.v b/test_regress/t/t_union_unpacked.v
similarity index 52%
rename from test_regress/t/t_union_unpacked_bad.v
rename to test_regress/t/t_union_unpacked.v
index d93b5ec5b..2cb7ccc39 100644
--- a/test_regress/t/t_union_unpacked_bad.v
+++ b/test_regress/t/t_union_unpacked.v
@@ -1,21 +1,22 @@
 // DESCRIPTION: Verilator: Verilog Test module
 //
 // This file ONLY is placed under the Creative Commons Public Domain, for
-// any use, without warranty, 2009 by Wilson Snyder.
+// any use, without warranty, 2023 by Wilson Snyder.
 // SPDX-License-Identifier: CC0-1.0
 
-module x;
+module t(/*AUTOARG*/);
 
-   typedef union {
-      int         a;
-   } union_t;
-
-   union_t b;
+   union {
+      bit [7:0] val1;
+      bit [3:0] val2;
+   } u;
 
    initial begin
-      b = 1;
-      if (b != 1) $stop;
+      u.val1 = 8'h7c;
+      if (u.val1 != 8'h7c) $stop;
+      if (u.val2 != 4'hc) $stop;
       $write("*-* All Finished *-*\n");
       $finish;
    end
+
 endmodule
diff --git a/test_regress/t/t_union_unpacked_bad.out b/test_regress/t/t_union_unpacked_bad.out
deleted file mode 100644
index 783f81c13..000000000
--- a/test_regress/t/t_union_unpacked_bad.out
+++ /dev/null
@@ -1,7 +0,0 @@
-%Warning-UNPACKED: t/t_union_unpacked_bad.v:9:12: Unsupported: Unpacked union
-                                                : ... In instance x
-    9 |    typedef union {
-      |            ^~~~~
-                   ... For warning description see https://verilator.org/warn/UNPACKED?v=latest
-                   ... Use "/* verilator lint_off UNPACKED */" and lint_on around source to disable this message.
-%Error: Exiting due to