diff --git a/Changes b/Changes
index ff6999eb6..0e5c75deb 100644
--- a/Changes
+++ b/Changes
@@ -27,7 +27,7 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ****  Fix signed extension problems with -Wno-WIDTH, bug729. [Clifford Wolf]
 
-****  Fix power operator calculation, bug730. [Clifford Wolf]
+****  Fix power operator calculation, bug730, bug735. [Clifford Wolf]
 
 ****  Fix Mac OS-X test issues. [Holger Waechtler]
 
diff --git a/src/V3Number.cpp b/src/V3Number.cpp
index 217073d12..5b083e336 100644
--- a/src/V3Number.cpp
+++ b/src/V3Number.cpp
@@ -47,6 +47,7 @@ V3Number::V3Number(VerilogString, FileLine* fileline, const string& str) {
 	    }
 	}
     }
+    opCleanThis();
 }
 
 V3Number::V3Number (FileLine* fileline, const char* sourcep) {
@@ -252,6 +253,7 @@ V3Number::V3Number (FileLine* fileline, const char* sourcep) {
 	setBit(obit, bitIs(obit-1));
 	obit++;
     }
+    opCleanThis();
 
     //printf("Dump \"%s\"  CP \"%s\"  B '%c' %d W %d\n", sourcep, value_startp, base, width(), m_value[0]);
 }
@@ -276,11 +278,13 @@ V3Number& V3Number::setQuad(vluint64_t value) {
     for (int i=0; i<words(); i++) m_value[i]=m_valueX[i] = 0;
     m_value[0] = value & VL_ULL(0xffffffff);
     m_value[1] = (value>>VL_ULL(32)) & VL_ULL(0xffffffff);
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setLong(uint32_t value) {
     for (int i=0; i<words(); i++) m_value[i]=m_valueX[i] = 0;
     m_value[0] = value;
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setLongS(vlsint32_t value) {
@@ -288,6 +292,7 @@ V3Number& V3Number::setLongS(vlsint32_t value) {
     union { uint32_t u; vlsint32_t s; } u;
     u.s = value;
     m_value[0] = u.u;
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setDouble(double value) {
@@ -314,14 +319,17 @@ V3Number& V3Number::setAllBits0() {
 }
 V3Number& V3Number::setAllBits1() {
     for (int i=0; i<words(); i++) { m_value[i]= ~0; m_valueX[i] = 0; }
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setAllBitsX() {
     for (int i=0; i<words(); i++) { m_value[i]=m_valueX[i] = ~0; }
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setAllBitsZ() {
     for (int i=0; i<words(); i++) { m_value[i]=0; m_valueX[i] = ~0; }
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::setMask(int nbits) {
@@ -341,6 +349,8 @@ string V3Number::ascii(bool prefixed, bool cleanVerilog) const {
 	if (width()!=64) out<<"%E-bad-width-double";
 	else out<<toDouble();
 	return out.str();
+    } else {
+	if ((m_value[words()-1] | m_valueX[words()-1]) & ~hiWordMask()) out<<"%E-hidden-bits";
     }
     if (prefixed) {
 	if (sized()) {
@@ -751,6 +761,7 @@ V3Number& V3Number::opCountOnes (const V3Number& lhs) {
     if (lhs.isFourState()) return setAllBitsX();
     setZero();
     m_value[0] = lhs.countOnes();
+    opCleanThis();
     return *this;
 }
 V3Number& V3Number::opIsUnknown (const V3Number& lhs) {
@@ -1291,6 +1302,7 @@ V3Number& V3Number::opModDivGuts(const V3Number& lhs, const V3Number& rhs, bool
 	}
 	UINFO(9, "  opmoddiv-1w  "<<lhs<<" "<<rhs<<" q="<<*this<<" rem=0x"<<hex<<k<<dec<<endl);
 	if (is_modulus) { setZero(); m_value[0] = k; }
+	opCleanThis();
 	return *this;
     }
 
@@ -1373,9 +1385,11 @@ V3Number& V3Number::opModDivGuts(const V3Number& lhs, const V3Number& rhs, bool
 	    m_value[i] = (un[i] >> s) | (shift_mask & (un[i+1] << (32-s)));
 	}
 	for (int i=vw; i<words; i++) m_value[i] = 0;
+	opCleanThis();
 	UINFO(9, "  opmoddiv-mod "<<lhs<<" "<<rhs<<" now="<<*this<<endl);
 	return *this;
     } else { // division
+	opCleanThis();
 	UINFO(9, "  opmoddiv-div "<<lhs<<" "<<rhs<<" now="<<*this<<endl);
 	return *this;
     }
@@ -1457,9 +1471,8 @@ V3Number& V3Number::opClean (const V3Number& lhs, uint32_t bits) {
 
 void V3Number::opCleanThis() {
     // Clean in place number
-    if (uint32_t okbits = (width() & 31)) {
-	m_value[words()-1] &= ((1UL<<okbits)-1);
-    }
+    m_value[words()-1]  &= hiWordMask();
+    m_valueX[words()-1] &= hiWordMask();
 }
 
 V3Number& V3Number::opSel (const V3Number& lhs, const V3Number& msb, const V3Number& lsb) {
diff --git a/src/V3Number.h b/src/V3Number.h
index eade3f973..d2bf4b628 100644
--- a/src/V3Number.h
+++ b/src/V3Number.h
@@ -103,6 +103,7 @@ private:
     }
 
     int words() const { return ((width()+31)/32); }
+    uint32_t hiWordMask() const { return VL_MASK_I(width()); }
 
     V3Number& opModDivGuts(const V3Number& lhs, const V3Number& rhs, bool is_modulus);
 
@@ -111,7 +112,7 @@ public:
     // CONSTRUCTORS
     V3Number(FileLine* fileline) { init(fileline, 1); }
     V3Number(FileLine* fileline, int width) { init(fileline, width); }  // 0=unsized
-    V3Number(FileLine* fileline, int width, uint32_t value) { init(fileline, width); m_value[0]=value; }
+    V3Number(FileLine* fileline, int width, uint32_t value) { init(fileline, width); m_value[0]=value; opCleanThis(); }
     V3Number(FileLine* fileline, const char* source);	// Create from a verilog 32'hxxxx number.
     V3Number(VerilogString, FileLine* fileline, const string& vvalue);
 
diff --git a/test_regress/t/t_math_pow4.pl b/test_regress/t/t_math_pow4.pl
new file mode 100755
index 000000000..f91289753
--- /dev/null
+++ b/test_regress/t/t_math_pow4.pl
@@ -0,0 +1,18 @@
+#!/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.
+
+compile (
+    );
+
+execute (
+    check_finished=>1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_math_pow4.v b/test_regress/t/t_math_pow4.v
new file mode 100644
index 000000000..392eb3f20
--- /dev/null
+++ b/test_regress/t/t_math_pow4.v
@@ -0,0 +1,68 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2014 by Clifford Wolf.
+
+module t (/*AUTOARG*/
+   // Inputs
+   clk
+   );
+   input clk;
+
+   integer 	cyc=0;
+
+   wire [31:0] y;
+   reg 	       a;
+   test004 sub (/*AUTOINST*/
+		// Outputs
+		.y			(y[31:0]),
+		// Inputs
+		.a			(a));
+
+   // Test loop
+   always @ (posedge clk) begin
+`ifdef TEST_VERBOSE
+      $write("[%0t] cyc==%0d a=%x y=%x\n",$time, cyc, a, y);
+`endif
+      cyc <= cyc + 1;
+      if (cyc==0) begin
+	 a <= 0;
+      end
+      else if (cyc==1) begin
+	 a <= 1;
+	 if (y != 32'h0) $stop;
+      end
+      else if (cyc==2) begin
+	 if (y != 32'h010000ff) $stop;
+      end
+      else if (cyc==99) begin
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+
+endmodule
+
+module test004(a, y);
+  input a;
+  output [31:0] y;
+
+  wire [7:0] y0;
+  wire [7:0] y1;
+  wire [7:0] y2;
+  wire [7:0] y3;
+  assign y = {y0,y1,y2,y3};
+
+  localparam [7:0] v0 = +8'sd1 ** -8'sd2; //'h01
+  localparam [7:0] v1 = +8'sd2 ** -8'sd2; //'h00
+  localparam [7:0] v2 = -8'sd2 ** -8'sd3; //'h00
+  localparam [7:0] v3 = -8'sd1 ** -8'sd3; //'hff
+  localparam [7:0] zero = 0;
+
+   initial $display("v0=%x v1=%x v2=%x v3=%x", v0,v1,v2,v3);
+
+  assign y0 = a ? v0 : zero;
+  assign y1 = a ? v1 : zero;
+  assign y2 = a ? v2 : zero;
+  assign y3 = a ? v3 : zero;
+endmodule