diff --git a/src/libhsakmt.h b/src/libhsakmt.h
index 1a2ba979ff..d9eab68b51 100644
--- a/src/libhsakmt.h
+++ b/src/libhsakmt.h
@@ -67,7 +67,7 @@ extern int PAGE_SHIFT;
 #define ALIGN_UP(x,align) (((uint64_t)(x) + (align) - 1) & ~(uint64_t)((align)-1))
 #define ALIGN_UP_32(x,align) (((uint32_t)(x) + (align) - 1) & ~(uint32_t)((align)-1))
 #define PAGE_ALIGN_UP(x) ALIGN_UP(x,PAGE_SIZE)
-#define BITMASK(n) ((n) ? (UINT64_MAX >> (sizeof(UINT64_MAX) * CHAR_BIT - n)) : n)
+#define BITMASK(n) ((n) ? (UINT64_MAX >> (sizeof(UINT64_MAX) * CHAR_BIT - (n))) : 0)
 #define ARRAY_LEN(array) (sizeof(array) / sizeof(array[0]))
 
 /* HSA Thunk logging usage */