diff --git a/Changes b/Changes
index 1adee83c5..143508bb8 100644
--- a/Changes
+++ b/Changes
@@ -9,6 +9,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  For --xml, add additional information, bug1372. [Jonathan Kimmitt]
 
+****  Add circular typedef error, bug1388.  [Al Grant]
+
 ****  Fix FST tracing of wide arrays, bug1376. [Aleksander Osman]
 
 ****  Fix error when pattern assignment has too few elements, bug1378. [Viktor Tomov]
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index 62f3dac49..99a1df347 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -929,8 +929,15 @@ void AstRange::dump(std::ostream& str) {
     if (littleEndian()) str<<" [LITTLE]";
 }
 void AstRefDType::dump(std::ostream& str) {
+    static bool s_recursing = false;
     this->AstNodeDType::dump(str);
-    if (defp()) { str<<" -> "; defp()->dump(str); }
+    if (defp()) {
+        if (!s_recursing) {  // Prevent infinite dump if circular typedefs
+            s_recursing = true;
+            str<<" -> "; defp()->dump(str);
+            s_recursing = false;
+        }
+    }
     else { str<<" -> UNLINKED"; }
 }
 void AstNodeClassDType::dump(std::ostream& str) {
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 501e18035..a9a1557a9 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -1043,12 +1043,24 @@ private:
 	UINFO(4,"dtWidthed "<<nodep<<endl);
     }
     virtual void visit(AstRefDType* nodep) {
-	if (nodep->didWidthAndSet()) return;  // This node is a dtype & not both PRELIMed+FINALed
-	userIterateChildren(nodep, NULL);
-	if (nodep->subDTypep()) nodep->refDTypep(iterateEditDTypep(nodep, nodep->subDTypep()));
-	nodep->dtypeFrom(nodep->dtypeSkipRefp());
-	nodep->widthFromSub(nodep->subDTypep());
-	UINFO(4,"dtWidthed "<<nodep<<endl);
+        if (nodep->doingWidth()) {  // Early exit if have circular parameter definition
+            nodep->v3error("Typedef's type is circular: "<<nodep->prettyName());
+            nodep->dtypeSetLogicBool();
+            nodep->doingWidth(false);
+            return;
+        }
+        if (nodep->didWidthAndSet()) return;  // This node is a dtype & not both PRELIMed+FINALed
+        nodep->doingWidth(true);
+        userIterateChildren(nodep, NULL);
+        if (nodep->subDTypep()) nodep->refDTypep(iterateEditDTypep(nodep, nodep->subDTypep()));
+        // Effectively nodep->dtypeFrom(nodep->dtypeSkipRefp());
+        // But might be recursive, so instead manually recurse into the referenced type
+        if (!nodep->defp()) nodep->v3fatalSrc("Unlinked");
+        nodep->dtypeFrom(nodep->defp());
+        userIterate(nodep->defp(), NULL);
+        nodep->widthFromSub(nodep->subDTypep());
+        UINFO(4,"dtWidthed "<<nodep<<endl);
+        nodep->doingWidth(false);
     }
     virtual void visit(AstTypedef* nodep) {
 	if (nodep->didWidthAndSet()) return;  // This node is a dtype & not both PRELIMed+FINALed
diff --git a/test_regress/t/t_typedef_circ_bad.out b/test_regress/t/t_typedef_circ_bad.out
new file mode 100644
index 000000000..09126fefc
--- /dev/null
+++ b/test_regress/t/t_typedef_circ_bad.out
@@ -0,0 +1,2 @@
+%Error: t/t_typedef_circ_bad.v:5: Typedef's type is circular: a_t
+%Error: Exiting due to
diff --git a/test_regress/t/t_typedef_circ_bad.pl b/test_regress/t/t_typedef_circ_bad.pl
new file mode 100755
index 000000000..e88bd5043
--- /dev/null
+++ b/test_regress/t/t_typedef_circ_bad.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+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 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.
+
+scenarios(vlt_all => 1);
+
+compile(
+    v_flags2 => ["--lint-only"],
+    fails => $Self->{vlt_all},
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_typedef_circ_bad.v b/test_regress/t/t_typedef_circ_bad.v
new file mode 100644
index 000000000..5c2075242
--- /dev/null
+++ b/test_regress/t/t_typedef_circ_bad.v
@@ -0,0 +1,6 @@
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2019 by Wilson Snyder
+
+typedef a_t;
+typedef a_t b_t;
+typedef b_t a_t;