diff --git a/Changes b/Changes
index f2cad212f..060d0d189 100644
--- a/Changes
+++ b/Changes
@@ -7,10 +7,12 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***  Support $ceil, $floor, etc.  [Alex Solomatnikov]
 
-***  Fix --help output to go to stderr, not stdout, bug397.  [Ruben Diez]
-
 ***  Add configure options for cc warnings and extended tests.  [Ruben Diez]
 
+***  Fix UNDRIVEN warnings inside DPI import functions.  [Ruben Diez]
+
+***  Fix --help output to go to stderr, not stdout, bug397.  [Ruben Diez]
+
 **** Fix MSVC compile warning with trunc/round, bug394. [Amir Gonnen]
 
 **** Fix autoconf and Makefile warnings, bug396.  [Ruben Diez]
diff --git a/src/V3Undriven.cpp b/src/V3Undriven.cpp
index fe7c801df..dcbdbfb28 100644
--- a/src/V3Undriven.cpp
+++ b/src/V3Undriven.cpp
@@ -217,6 +217,7 @@ private:
     // STATE
     vector<UndrivenVarEntry*>	m_entryps;	// Nodes to delete when we are finished
     bool		m_markBoth;	// Mark as driven+used
+    AstNodeFTask*	m_taskp;	// Current task
 
     // METHODS
     static int debug() {
@@ -241,12 +242,14 @@ private:
     virtual void visit(AstVar* nodep, AstNUser*) {
 	UndrivenVarEntry* entryp = getEntryp (nodep);
 	if (nodep->isInput()
-	    || nodep->isSigPublic() || nodep->isSigUserRWPublic()) {
+	    || nodep->isSigPublic() || nodep->isSigUserRWPublic()
+	    || (m_taskp && (m_taskp->dpiImport() || m_taskp->dpiExport()))) {
 	    entryp->drivenWhole();
 	}
 	if (nodep->isOutput()
 	    || nodep->isSigPublic() || nodep->isSigUserRWPublic()
-	    || nodep->isSigUserRdPublic()) {
+	    || nodep->isSigUserRdPublic()
+	    || (m_taskp && (m_taskp->dpiImport() || m_taskp->dpiExport()))) {
 	    entryp->usedWhole();
 	}
 	// Discover variables used in bit definitions, etc
@@ -284,6 +287,13 @@ private:
 	m_markBoth = prevMark;
     }
 
+    virtual void visit(AstNodeFTask* nodep, AstNUser*) {
+	AstNodeFTask* prevTaskp = m_taskp;
+	m_taskp = nodep;
+	nodep->iterateChildren(*this);
+	m_taskp = prevTaskp;
+    }
+
     // Until we support tables, primitives will have undriven and unused I/Os
     virtual void visit(AstPrimitive* nodep, AstNUser*) {}
 
@@ -303,6 +313,7 @@ public:
     // CONSTUCTORS
     UndrivenVisitor(AstNetlist* nodep) {
 	m_markBoth = false;
+	m_taskp = NULL;
 	nodep->accept(*this);
     }
     virtual ~UndrivenVisitor() {
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index 0eb5a4500..94245cf07 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -65,6 +65,7 @@ Getopt::Long::config ("pass_through");
 if (! GetOptions (
 		  "benchmark:i" => sub { $opt_benchmark = $_[1] ? $_[1] : 1; },
 		  "debug"	=> \&debug,
+	  	  #debugi	   see parameter()
 		  "atsim|athdl!"=> \$opt_atsim,
 		  "gdb!"	=> \$opt_gdb,
 		  "gdbbt!"	=> \$opt_gdbbt,
@@ -84,6 +85,7 @@ if (! GetOptions (
 		  "vcs!"	=> \$opt_vcs,
 		  "verbose!"	=> \$opt_verbose,
 		  "verilated_debug!"	=> \$Opt_Verilated_Debug,
+	  	  #W		   see parameter()
 		  "<>"		=> \&parameter,
 		  )) {
     die "%Error: Bad usage, try '$0 --help'\n";
@@ -205,6 +207,9 @@ sub parameter {
 	push @Opt_Driver_Verilator_Flags, $param;
 	$_Parameter_Next_Level = $param;
     }
+    elsif ($param =~ /^-?-W/) {
+	push @Opt_Driver_Verilator_Flags, $param;
+    }
     else {
 	die "%Error: Unknown parameter: $param\n";
     }
diff --git a/test_regress/t/t_dpi_export.pl b/test_regress/t/t_dpi_export.pl
index bbe758e10..494e1c8fc 100755
--- a/test_regress/t/t_dpi_export.pl
+++ b/test_regress/t/t_dpi_export.pl
@@ -11,7 +11,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 compile (
 	 # Amazingly VCS, NC and Verilator all just accept the C file here!
-	 v_flags2 => ["t/t_dpi_export_c.cpp"],
+	 v_flags2 => ["-Wall -Wno-DECLFILENAME t/t_dpi_export_c.cpp"],
 	 verilator_flags2 => ["-no-l2name"],
 	 );
 
diff --git a/test_regress/t/t_dpi_import.pl b/test_regress/t/t_dpi_import.pl
index 708ef7b4a..d9776a553 100755
--- a/test_regress/t/t_dpi_import.pl
+++ b/test_regress/t/t_dpi_import.pl
@@ -9,7 +9,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 compile (
 	 # Amazingly VCS, NC and Verilator all just accept the C file here!
-	 v_flags2 => ["t/t_dpi_import_c.cpp"],
+	 v_flags2 => ["-Wall -Wno-DECLFILENAME t/t_dpi_import_c.cpp"],
 	 );
 
 execute (
diff --git a/test_regress/t/t_dpi_import.v b/test_regress/t/t_dpi_import.v
index c6686cfe6..ae2ddec79 100644
--- a/test_regress/t/t_dpi_import.v
+++ b/test_regress/t/t_dpi_import.v
@@ -73,11 +73,11 @@ module t ();
    import "DPI-C" dpii_fa_bit =  function int oth_f_int2(input int i);
 
    bit       	i_b,	o_b;
-   bit [7:0]	i_b8,	o_b8;
-   bit [8:0]	i_b9,	o_b9;
-   bit [15:0]	i_b16,	o_b16;
-   bit [16:0]	i_b17,	o_b17;
-   bit [31:0]	i_b32,	o_b32;
+   bit [7:0]    i_b8;
+   bit [8:0]	i_b9;
+   bit [15:0]	i_b16;
+   bit [16:0]   i_b17;
+   bit [31:0]	i_b32;
    bit [32:0]	i_b33,	o_b33;
    bit [63:0]	i_b64,	o_b64;
    bit [94:0]	i_b95,	o_b95;
@@ -87,19 +87,21 @@ module t ();
    byte		i_y,	o_y;
    shortint	i_s,	o_s;
    longint	i_l,	o_l;
+   // verilator lint_off UNDRIVEN
    chandle	i_c,	o_c;
    string 	i_n,	o_n;
+   // verilator lint_on UNDRIVEN
    real 	i_d,	o_d;
 `ifndef NO_SHORTREAL
    shortreal 	i_f,	o_f;
 `endif
 
-   bit [127:0] wide;
+   bit [94:0] wide;
 
    bit [6*8:1] string6;
 
    initial begin
-      wide = 128'h36f3e51d15caff7a73c48afee4ffcb57;
+      wide = 95'h15caff7a73c48afee4ffcb57;
 
       i_b  = 1'b1;
       i_b8  = {1'b1,wide[8-2:0]};