1 files changed, 1 insertions, 1 deletions
diff --git a/ptr_chck.c b/ptr_chck.c
index d8076e84..5b3cc0a6 100644
--- a/ptr_chck.c
+++ b/ptr_chck.c
@@ -226,7 +226,7 @@ GC_API void * GC_CALL GC_is_visible(void *p)
                     if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
                     break;
                 case GC_DS_BITMAP:
-                    if ((ptr_t)p - (ptr_t)base
+                    if ((word)((ptr_t)p - (ptr_t)base)
                          >= WORDS_TO_BYTES(BITMAP_BITS)
                          || ((word)p & (sizeof(word) - 1))) goto fail;
                     if (!(((word)1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))