diff --git a/src/lj_def.h b/src/lj_def.h
index c7600d33..e9249e0d 100644
--- a/src/lj_def.h
+++ b/src/lj_def.h
@@ -254,19 +254,19 @@ static LJ_AINLINE uint32_t lj_fls(uint32_t x)
   return _CountLeadingZeros(x) ^ 31;
 }
 #else
-unsigned char _BitScanForward(uint32_t *, unsigned long);
-unsigned char _BitScanReverse(uint32_t *, unsigned long);
+unsigned char _BitScanForward(unsigned long *, unsigned long);
+unsigned char _BitScanReverse(unsigned long *, unsigned long);
 #pragma intrinsic(_BitScanForward)
 #pragma intrinsic(_BitScanReverse)
 
 static LJ_AINLINE uint32_t lj_ffs(uint32_t x)
 {
-  uint32_t r; _BitScanForward(&r, x); return r;
+  unsigned long r; _BitScanForward(&r, x); return (uint32_t)r;
 }
 
 static LJ_AINLINE uint32_t lj_fls(uint32_t x)
 {
-  uint32_t r; _BitScanReverse(&r, x); return r;
+  unsigned long r; _BitScanReverse(&r, x); return (uint32_t)r;
 }
 #endif