diff --git a/Changes b/Changes
index d184e7bd1..0d2803490 100644
--- a/Changes
+++ b/Changes
@@ -5,6 +5,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 * Verilator 3.81***
 
+**** Throw UNUSED/UNDRIVEN only once per net in a parametrized module.
+
 **** Fix false BLKSEQ on non-unrolled for loop indexes.  [Jeff Winston]
 
 **** Fix block comment not separating identifiers, bug311. [Gene Sullivan]
diff --git a/src/V3Begin.cpp b/src/V3Begin.cpp
index 4aa08862b..eecea0e6b 100644
--- a/src/V3Begin.cpp
+++ b/src/V3Begin.cpp
@@ -162,7 +162,7 @@ private:
 	    m_ifDepth = -1;
 	} else if (++m_ifDepth > v3Global.opt.ifDepth()) {
 	    nodep->v3warn(IFDEPTH,"Deep 'if' statement; suggest unique/priority to avoid slow logic");
-	    nodep->fileline()->warnOn(V3ErrorCode::IFDEPTH, false);  // Warn only once
+	    nodep->fileline()->modifyWarnOff(V3ErrorCode::IFDEPTH, true);  // Warn only once
 	    m_ifDepth = -1;
 	}
 	nodep->iterateChildren(*this);
diff --git a/src/V3LinkParse.cpp b/src/V3LinkParse.cpp
index d7f617893..67dec96cd 100644
--- a/src/V3LinkParse.cpp
+++ b/src/V3LinkParse.cpp
@@ -33,6 +33,7 @@
 #include <cstdarg>
 #include <unistd.h>
 #include <map>
+#include <set>
 #include <algorithm>
 #include <vector>
 
@@ -47,11 +48,14 @@ class LinkParseVisitor : public AstNVisitor {
 private:
     // NODE STATE
     // Cleared on netlist
-    //  AstNode::user()		-> bool.  True if processed
+    //  AstNode::user1()	-> bool.  True if processed
+    //  AstNode::user2()	-> bool.  True if fileline recomputed
     AstUser1InUse	m_inuser1;
+    AstUser2InUse	m_inuser2;
 
     // TYPES
     typedef map <pair<void*,string>,AstTypedef*> ImplTypedefMap;
+    typedef set <FileLine*> FileLineSet;
 
     // STATE
     string	m_dotText;	// Dotted module text we are building for a dotted node, passed up
@@ -60,6 +64,7 @@ private:
     AstText*	m_baseTextp;	// Lowest TEXT node that needs replacement with varref
     AstVar*	m_varp;		// Variable we're under
     ImplTypedefMap	m_implTypedef;	// Created typedefs for each <container,name>
+    FileLineSet		m_filelines;	// Filelines that have been seen
 
     // METHODS
     static int debug() {
@@ -68,6 +73,21 @@ private:
 	return level;
     }
 
+    void cleanFileline(AstNode* nodep) {
+	if (!nodep->user2Inc()) {  // Process once
+	    // We make all filelines unique per AstNode.  This allows us to
+	    // later turn off messages on a fileline when an issue is found
+	    // so that messages on replicated blocks occur only once,
+	    // without suppressing other token's messages as a side effect.
+	    // We could have verilog.l create a new one on every token,
+	    // but that's a lot more structures than only doing AST nodes.
+	    if (m_filelines.find(nodep->fileline()) != m_filelines.end()) {
+		nodep->fileline(new FileLine(nodep->fileline()));
+	    }
+	    m_filelines.insert(nodep->fileline());
+	}
+    }
+
     void checkExpected(AstNode* nodep) {
 	if (m_exp != AstParseRefExp::PX_NONE) {
 	    nodep->v3fatalSrc("Tree syntax error: Not expecting "<<nodep->type()<<" under a "<<nodep->backp()->type());
@@ -78,6 +98,7 @@ private:
     // VISITs
     virtual void visit(AstNodeFTaskRef* nodep, AstNUser*) {
 	if (!nodep->user1Inc()) {  // Process only once.
+	    cleanFileline(nodep);
 	    UINFO(5,"   "<<nodep<<endl);
 	    checkExpected(nodep);
 	    // Due to a need to get the arguments, the ParseRefs are under here,
@@ -141,6 +162,7 @@ private:
     }
     virtual void visit(AstDot* nodep, AstNUser*) {
 	UINFO(5,"     "<<nodep<<endl);
+	cleanFileline(nodep);
 	if (m_inModDot) { // Already under dot, so this is {modulepart} DOT {modulepart}
 	    m_dotText = "";
 	    nodep->lhsp()->iterateAndNext(*this);
@@ -165,6 +187,7 @@ private:
     }
     virtual void visit(AstSelBit* nodep, AstNUser*) {
 	if (!nodep->user1Inc()) {  // Process only once.
+	    cleanFileline(nodep);
 	    if (m_inModDot) { // Already under dot, so this is {modulepart} DOT {modulepart}
 		m_dotText = "";
 		nodep->lhsp()->iterateAndNext(*this);
@@ -193,6 +216,7 @@ private:
     virtual void visit(AstNodePreSel* nodep, AstNUser*) {
 	// Excludes simple AstSel, see above
 	if (!nodep->user1Inc()) {  // Process only once.
+	    cleanFileline(nodep);
 	    if (m_inModDot) { // Already under dot, so this is {modulepart} DOT {modulepart}
 		nodep->v3error("Syntax Error: Range ':', '+:' etc are not allowed in the cell part of a dotted reference");
 	    } else if (m_exp==AstParseRefExp::PX_FUNC) {
@@ -215,6 +239,7 @@ private:
     }
     virtual void visit(AstText* nodep, AstNUser*) {
 	if (!nodep->user1Inc()) {  // Process only once.
+	    cleanFileline(nodep);
 	    if (m_exp != AstParseRefExp::PX_NONE) {
 		UINFO(7,"      "<<nodep<<endl);
 		if (m_inModDot) {  // Dotted part, just pass up
@@ -228,6 +253,7 @@ private:
     }
     virtual void visit(AstEnumItem* nodep, AstNUser*) {
 	// Expand ranges
+	cleanFileline(nodep);
 	nodep->iterateChildren(*this);
 	if (nodep->rangep()) {
 	    if (!nodep->rangep()->msbp()->castConst()
@@ -251,12 +277,14 @@ private:
 
 
     virtual void visit(AstVar* nodep, AstNUser*) {
+	cleanFileline(nodep);
 	m_varp = nodep;
 	nodep->iterateChildren(*this);
 	m_varp = NULL;
     }
 
     virtual void visit(AstAttrOf* nodep, AstNUser*) {
+	cleanFileline(nodep);
 	nodep->iterateChildren(*this);
 	if (nodep->attrType() == AstAttrType::VAR_CLOCK) {
 	    if (!m_varp) nodep->v3fatalSrc("Attribute not attached to variable");
@@ -303,6 +331,7 @@ private:
     virtual void visit(AstAlwaysPublic* nodep, AstNUser*) {
 	// AlwaysPublic was attached under a var, but it's a statement that should be
 	// at the same level as the var
+	cleanFileline(nodep);
 	nodep->iterateChildren(*this);
 	if (m_varp) {
 	    nodep->unlinkFrBack();
@@ -315,6 +344,7 @@ private:
     }
 
     virtual void visit(AstDefImplicitDType* nodep, AstNUser*) {
+	cleanFileline(nodep);
 	UINFO(8,"   DEFIMPLICIT "<<nodep<<endl);
 	// Must remember what names we've already created, and combine duplicates
 	// so that for "var enum {...} a,b" a & b will share a common typedef
@@ -351,6 +381,7 @@ private:
 
     virtual void visit(AstNode* nodep, AstNUser*) {
 	// Default: Just iterate
+	cleanFileline(nodep);
 	checkExpected(nodep);  // So we detect node types we forgot to list here
 	nodep->iterateChildren(*this);
     }
diff --git a/src/V3Undriven.cpp b/src/V3Undriven.cpp
index 67286c457..3c1c539ae 100644
--- a/src/V3Undriven.cpp
+++ b/src/V3Undriven.cpp
@@ -170,27 +170,36 @@ public:
 		// thus undriven+unused bits get UNUSED warnings, as they're not as buggy.
 		if (!unusedMatch(nodep)) {
 		    nodep->v3warn(UNUSED, "Signal is not driven, nor used: "<<nodep->prettyName());
+		    nodep->fileline()->modifyWarnOff(V3ErrorCode::UNUSED, true);  // Warn only once
 		}
 	    } else if (allD && !anyU) {
 		if (!unusedMatch(nodep)) {
 		    nodep->v3warn(UNUSED, "Signal is not used: "<<nodep->prettyName());
+		    nodep->fileline()->modifyWarnOff(V3ErrorCode::UNUSED, true);  // Warn only once
 		}
 	    } else if (!anyD && allU) {
 		nodep->v3warn(UNDRIVEN, "Signal is not driven: "<<nodep->prettyName());
+		nodep->fileline()->modifyWarnOff(V3ErrorCode::UNDRIVEN, true);  // Warn only once
 	    } else {
 		// Bits have different dispositions
+		bool setU=false; bool setD=false;
 		if (anynotDU && !unusedMatch(nodep)) {
 		    nodep->v3warn(UNUSED, "Bits of signal are not driven, nor used: "<<nodep->prettyName()
 				  <<bitNames(BN_BOTH));
+		    setU=true;
 		}
 		if (anyDnotU && !unusedMatch(nodep)) {
 		    nodep->v3warn(UNUSED, "Bits of signal are not used: "<<nodep->prettyName()
 				  <<bitNames(BN_UNUSED));
+		    setU=true;
 		}
 		if (anyUnotD) {
 		    nodep->v3warn(UNDRIVEN, "Bits of signal are not driven: "<<nodep->prettyName()
 				  <<bitNames(BN_UNDRIVEN));
+		    setD=true;
 		}
+		if (setU) nodep->fileline()->modifyWarnOff(V3ErrorCode::UNUSED, true);  // Warn only once
+		if (setD) nodep->fileline()->modifyWarnOff(V3ErrorCode::UNDRIVEN, true);  // Warn only once
 	    }
 	}
     }
diff --git a/test_regress/t/t_cdc_async_bad.pl b/test_regress/t/t_cdc_async_bad.pl
index 5878fd9d6..02e1d5efc 100755
--- a/test_regress/t/t_cdc_async_bad.pl
+++ b/test_regress/t/t_cdc_async_bad.pl
@@ -16,6 +16,7 @@ compile (
 %Warning-CDCRSTLOGIC: Use "/\* verilator lint_off CDCRSTLOGIC \*/" and lint_on around source to disable this message.
 %Warning-CDCRSTLOGIC:      See details in obj_dir/t_cdc_async_bad/Vt_cdc_async_bad__cdc.txt
 %Warning-CDCRSTLOGIC: t/t_cdc_async_bad.v:\d+: Logic in path that feeds async reset, via signal: v.rst6a_bad_n
+%Warning-CDCRSTLOGIC: t/t_cdc_async_bad.v:\d+: Logic in path that feeds async reset, via signal: v.rst6b_bad_n
 %Warning-CDCRSTLOGIC: t/t_cdc_async_bad.v:\d+: Logic in path that feeds async reset, via signal: v.rst3_bad_n
 %Error: Exiting due to.*',
 	 );
diff --git a/test_regress/t/t_lint_once_bad.pl b/test_regress/t/t_lint_once_bad.pl
new file mode 100755
index 000000000..3576d17b1
--- /dev/null
+++ b/test_regress/t/t_lint_once_bad.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 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 (
+	 make_top_shell => 0,
+	 make_main => 0,
+	 v_flags2 => ["--lint-only -Wwarn-UNUSED"],
+	 verilator_make_gcc => 0,
+	 fails=>1,
+	 expect=>
+'%Warning-UNUSED: t/t_lint_once_bad.v:\d+: Signal is not driven, nor used: unus1
+%Warning-UNUSED: Use .* to disable this message.
+%Warning-UNUSED: t/t_lint_once_bad.v:\d+: Signal is not driven, nor used: unus2
+%Error: Exiting due to.*',
+	 ) if $Self->{v3};
+
+ok(1);
+1;
diff --git a/test_regress/t/t_lint_once_bad.v b/test_regress/t/t_lint_once_bad.v
new file mode 100644
index 000000000..c70b88e02
--- /dev/null
+++ b/test_regress/t/t_lint_once_bad.v
@@ -0,0 +1,19 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2006 by Wilson Snyder.
+
+// Check that we report warnings only once on parameterized modules
+// Also check that we don't suppress warnings on the same line
+
+module t ();
+   sub #(.A(1)) sub1();
+   sub #(.A(2)) sub2();
+   sub #(.A(3)) sub3();
+endmodule
+
+module sub;
+   parameter A = 0;
+
+   reg [A:0] unus1;    reg [A:0] unus2;
+endmodule