diff --git a/libmpcodecs/vf_divtc.c b/libmpcodecs/vf_divtc.c
index fa2918135e..5eba70bb8b 100644
--- a/libmpcodecs/vf_divtc.c
+++ b/libmpcodecs/vf_divtc.c
@@ -128,7 +128,7 @@ static unsigned int checksum_plane(unsigned char *p, unsigned char *z,
    unsigned int shift;
    uint32_t sum, t;
    unsigned char *e, *e2;
-#if __WORDSIZE==64
+#if HAVE_FAST_64BIT
    typedef uint64_t wsum_t;
 #else
    typedef uint32_t wsum_t;
@@ -143,7 +143,7 @@ static unsigned int checksum_plane(unsigned char *p, unsigned char *z,
       for(wsum=0, e2=e-sizeof(wsum_t)+1; p<e2; p+=sizeof(wsum_t))
 	 wsum^=*(wsum_t *)p;
 
-#if __WORDSIZE==64
+#if HAVE_FAST_64BIT
       t=be2me_32((uint32_t)(wsum>>32^wsum));
 #else
       t=be2me_32(wsum);