diff --git a/core/sys/windows/bitop.c b/core/sys/windows/bitop.c
index 60921d4..b5778d4 100644
--- a/core/sys/windows/bitop.c
+++ b/core/sys/windows/bitop.c
@@ -23,7 +23,11 @@ int b_popcountl(long v)
 	}
 
 	if (cpu_supports_popcnt == CPU_FEATURE_YES) {
+#if _M_AMD64 == 100
 		return __popcnt64(v);
+#else
+		return __popcnt(v);
+#endif
 	}
 	
 	assert(0 && "CPU does not support popcount!");
@@ -34,7 +38,13 @@ int b_ctzl(long v)
 {
 	unsigned long trailing_zero = 0;
 
-	if (_BitScanForward64(&trailing_zero, v)) {
+#if _M_AMD64 == 100
+	int x = _BitScanForward64(&trailing_zero, v);
+#else
+	int x = _BitScanForward(&trailing_zero, v);
+#endif
+
+	if (x) {
 		return trailing_zero;
 	} else {
 		return 64;
@@ -45,7 +55,13 @@ int b_clzl(long v)
 {
 	unsigned long leading_zero = 0;
 
-	if (_BitScanReverse64(&leading_zero, v)) {
+#if _M_AMD64 == 100
+	int x = _BitScanReverse64(&leading_zero, v);
+#else
+	int x = _BitScanReverse(&leading_zero, v);
+#endif
+
+	if (x) {
 		return 64 - leading_zero;
 	} else {
 		// Same remarks as above