diff --git a/Changes b/Changes
index aa6ff3bd8..b7ffb07e4 100644
--- a/Changes
+++ b/Changes
@@ -9,6 +9,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***  Add /*verilator public_flat_rw*/ for timing-specific public access.
 
+***  Fix word size to match uint64_t on -m64 systems, bug238. [Joe Eiler]
+
 **** Improve error handling on slices of arrays, bug226. [by Bryon Bradley]
 
 **** Report errors when extra underscores used in meta-comments.
diff --git a/include/verilated_vcd_c.cpp b/include/verilated_vcd_c.cpp
index d86dab751..57bd4cf6f 100644
--- a/include/verilated_vcd_c.cpp
+++ b/include/verilated_vcd_c.cpp
@@ -234,7 +234,7 @@ void VerilatedVcd::printStr (const char* str) {
 
 void VerilatedVcd::printQuad (vluint64_t n) {
     char buf [100];
-    sprintf(buf,"%" VL_PRI64 "u",(long long unsigned)n);
+    sprintf(buf,"%" VL_PRI64 "u", n);
     printStr(buf);
 }
 
diff --git a/include/verilatedos.h b/include/verilatedos.h
index 00243df91..07c01ec2e 100644
--- a/include/verilatedos.h
+++ b/include/verilatedos.h
@@ -126,8 +126,13 @@ typedef unsigned long		uint32_t;	///< 32-bit unsigned type (backward compatibili
 typedef long			vlsint32_t;	///< 32-bit signed type
 typedef unsigned long		vluint32_t;	///< 32-bit unsigned type
 # endif
+# if defined(__WORDSIZE) && (__WORDSIZE == 64)
+typedef long			vlsint64_t;	///< 64-bit signed type
+typedef unsigned long		vluint64_t;	///< 64-bit unsigned type
+# else
 typedef long long		vlsint64_t;	///< 64-bit signed type
-typedef unsigned long long      vluint64_t;	///< 64-bit unsigned type
+typedef unsigned long long	vluint64_t;	///< 64-bit unsigned type
+# endif
 
 #elif defined(_WIN32) && defined(_MSC_VER)
 
@@ -149,8 +154,13 @@ typedef uint8_t			vluint8_t;	///< 32-bit unsigned type
 typedef uint16_t		vluint16_t;	///< 32-bit unsigned type
 typedef int			vlsint32_t;	///< 32-bit signed type
 typedef uint32_t		vluint32_t;	///< 32-bit signed type
+# if defined(__WORDSIZE) && (__WORDSIZE == 64)
+typedef long			vlsint64_t;	///< 64-bit signed type
+typedef unsigned long		vluint64_t;	///< 64-bit unsigned type
+# else
 typedef long long		vlsint64_t;	///< 64-bit signed type
 typedef unsigned long long	vluint64_t;	///< 64-bit unsigned type
+# endif
 #endif
 
 //=========================================================================
@@ -160,7 +170,11 @@ typedef unsigned long long	vluint64_t;	///< 64-bit unsigned type
 #ifdef _WIN32
 # define VL_PRI64 "I64"
 #else // Linux or compliant Unix flavors
-# define VL_PRI64 "ll"
+# if defined(__WORDSIZE) && (__WORDSIZE == 64)
+#  define VL_PRI64 "l"
+# else
+#  define VL_PRI64 "ll"
+# endif
 #endif
 
 //=========================================================================
diff --git a/nodist/spdiff b/nodist/spdiff
index 516b03ac3..6f9850b45 100755
--- a/nodist/spdiff
+++ b/nodist/spdiff
@@ -126,6 +126,7 @@ sub prep {
 	#
 	$wholefile =~ s/\b(uint[0-9]+_t)/vl$1/g;
 	$wholefile =~ s/%ll/%" VL_PRI64 "/g;
+	$wholefile =~ s/\(long long unsigned\)n/ n/g;  # printQuad
 	#
 	$wholefile =~ s/\bSP_SC_BV/VL_SC_BV/g;
 	$wholefile =~ s/\bSP_UNLIKELY/VL_UNLIKELY/g;
diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index c8af37f14..0b78acc28 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -543,17 +543,18 @@ public:
 	    }
 	    for (int word=VL_WORDS_I(nodep->num().minWidth())-1; word>0; word--) {
 		// Only 32 bits - llx + long long here just to appease CPP format warning
-		ofp()->printf(",0x%08" VL_PRI64 "x", (long long)(nodep->num().dataWord(word)));
+		ofp()->printf(",0x%08" VL_PRI64 "x", (vluint64_t)(nodep->num().dataWord(word)));
 	    }
-	    ofp()->printf(",0x%08" VL_PRI64 "x)", (long long)(nodep->num().dataWord(0)));
+	    ofp()->printf(",0x%08" VL_PRI64 "x)", (vluint64_t)(nodep->num().dataWord(0)));
 	} else if (nodep->isQuad()) {
 	    vluint64_t num = nodep->toUQuad();
-	    if (num<10) ofp()->printf("VL_ULL(%" VL_PRI64 "d)", (long long)num);
-	    else ofp()->printf("VL_ULL(0x%" VL_PRI64 "x)", (long long)num);
+	    if (num<10) ofp()->printf("VL_ULL(%" VL_PRI64 "d)", num);
+	    else ofp()->printf("VL_ULL(0x%" VL_PRI64 "x)", num);
 	} else {
 	    uint32_t num = nodep->toUInt();
+	    // Only 32 bits - llx + long long here just to appease CPP format warning
 	    if (num<10) puts(cvtToStr(num));
-	    else ofp()->printf("0x%" VL_PRI64 "x", (long long)num);
+	    else ofp()->printf("0x%" VL_PRI64 "x", (vluint64_t)num);
 	    //Unneeded-Causes %lx format warnings:
 	    //  if (!nodep->num().isSigned() && (num & (1UL<<31))) puts("U");
 	}
diff --git a/test_regress/t/t_leak.cpp b/test_regress/t/t_leak.cpp
index 3af174bf2..4264a67b0 100644
--- a/test_regress/t/t_leak.cpp
+++ b/test_regress/t/t_leak.cpp
@@ -28,7 +28,7 @@ long long get_memory_usage() {
     if (!fp) return 0;
 
     int		ps_ign;
-    long long	ps_vsize, ps_rss;
+    vluint64_t	ps_vsize, ps_rss;
     int items = fscanf(fp, ("%d (%*[^) ]) %*1s %d %*d %*d %*d %*d %u"
 			    " %u %u %u %u %d %d %d %d"
 			    " %*d %*d %*u %*u %d %" VL_PRI64 "u %" VL_PRI64 "u "),
@@ -61,7 +61,7 @@ void make_and_destroy () {
 }
 
 int main (int argc, char *argv[]) {
-    long long firstUsage = get_memory_usage();
+    vluint64_t firstUsage = get_memory_usage();
 
     // Warmup phase
     for (int i=0; i<1000; i++) {
@@ -77,7 +77,7 @@ int main (int argc, char *argv[]) {
 	}
     }
 
-    long long leaked = get_memory_usage() - firstUsage;
+    vluint64_t leaked = get_memory_usage() - firstUsage;
     if (leaked > 64*1024) {  // Have to allow some slop for this code.
 	printf ("Leaked %" VL_PRI64 "d bytes, or ~ %" VL_PRI64 "d bytes/construt\n", leaked, leaked/loops);
 	vl_fatal(__FILE__,__LINE__,"top", "Leaked memory\n");