diff --git a/Changes b/Changes
index 0d2803490..97b65dc0d 100644
--- a/Changes
+++ b/Changes
@@ -5,6 +5,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 * Verilator 3.81***
 
+**** Report errors on duplicated pins, bug321.  [Christian Leber]
+
 **** Throw UNUSED/UNDRIVEN only once per net in a parametrized module.
 
 **** Fix false BLKSEQ on non-unrolled for loop indexes.  [Jeff Winston]
diff --git a/TODO b/TODO
index adaf3a994..222e4de25 100644
--- a/TODO
+++ b/TODO
@@ -67,6 +67,10 @@ Usability:
 	  	    #### non-comment lines, ##### ops, ### KB model size
 	* Default the --l2name to remove extra "v" level of hierarchy (flag to make "top")
 
+Lint:
+	* CDCRSTLOGIC should allow filtering with paths
+	  "waive CDCRSTLOGIC --from a.b.sig  --to a.c.sig --via OR"
+
 Internal Code:
 	* Eliminate the AstNUser* passed to all visitors; its only needed in V3Width,
 	  and removing it will speed up and simplify all the other code.
diff --git a/src/V3Link.cpp b/src/V3Link.cpp
index a76619bdd..72152f781 100644
--- a/src/V3Link.cpp
+++ b/src/V3Link.cpp
@@ -55,9 +55,11 @@ private:
     //   AstNodeModule::user4p() // V3SymTable*    Module's Symbol table
     //   AstNodeFTask::user4p()	// V3SymTable*    Local Symbol table
     //   AstBegin::user4p()	// V3SymTable*    Local Symbol table
+    //   AstVar::user5p()	// AstPin*	  True if port attached to a pin
     AstUser2InUse	m_inuser2;
     AstUser3InUse	m_inuser3;
     AstUser4InUse	m_inuser4;
+    AstUser5InUse	m_inuser5;
 
     // ENUMS
     enum IdState {		// Which loop through the tree
@@ -551,6 +553,7 @@ private:
     virtual void visit(AstCell* nodep, AstNUser*) {
 	// Cell: Resolve its filename.  If necessary, parse it.
 	m_cellp = nodep;
+	AstNode::user5ClearTree();
 	if (m_idState==ID_FIND) {
 	    // Add to list of all cells, for error checking and defparam's
 	    findAndInsertAndCheck(nodep, nodep->name());
@@ -635,6 +638,12 @@ private:
 		nodep->v3error("Pin is not an in/out/inout/param: "<<nodep->prettyName());
 	    } else {
 		nodep->modVarp(refp);
+		if (refp->user5p() && refp->user5p()->castNode()!=nodep) {
+		    nodep->v3error("Duplicate pin connection: "<<nodep->prettyName());
+		    refp->user5p()->castNode()->v3error("... Location of original pin connection");
+		} else {
+		    refp->user5p(nodep);
+		}
 	    }
 	    nodep->iterateChildren(*this);
 	}
diff --git a/test_regress/t/t_lint_pindup_bad.pl b/test_regress/t/t_lint_pindup_bad.pl
new file mode 100755
index 000000000..4c453fad1
--- /dev/null
+++ b/test_regress/t/t_lint_pindup_bad.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 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.
+
+compile (
+    v_flags2 => ["--lint-only"],
+    fails=>1,
+    verilator_make_gcc => 0,
+    make_top_shell => 0,
+    make_main => 0,
+    expect=>
+'%Error: t/t_lint_pindup_bad.v:\d+: Duplicate pin connection: i
+%Error: t/t_lint_pindup_bad.v:\d+: ... Location of original pin connection
+%Error: t/t_lint_pindup_bad.v:\d+: Duplicate pin connection: P
+%Error: t/t_lint_pindup_bad.v:\d+: ... Location of original pin connection
+%Error: Exiting due to.*',
+    ) if $Self->{v3};
+
+ok(1);
+1;
diff --git a/test_regress/t/t_lint_pindup_bad.v b/test_regress/t/t_lint_pindup_bad.v
new file mode 100644
index 000000000..167627b99
--- /dev/null
+++ b/test_regress/t/t_lint_pindup_bad.v
@@ -0,0 +1,31 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2010 by Wilson Snyder.
+
+module t
+   (
+   output wire o,
+   input wire i,
+   input wire i2
+   );
+
+   sub
+     #(.P(2), .P(3))
+   sub (.o(o),
+	.i(i),
+	.i(i2),
+	);
+
+endmodule
+
+module sub
+  #(parameter P=1)
+  (
+   output wire o,
+   input wire i
+   );
+
+   assign o = ~i;
+
+endmodule