diff --git a/src/hb-atomic-private.hh b/src/hb-atomic-private.hh
index 2d5675792..934384014 100644
--- a/src/hb-atomic-private.hh
+++ b/src/hb-atomic-private.hh
@@ -89,9 +89,9 @@ typedef int32_t hb_atomic_int_impl_t;
 #define hb_atomic_ptr_impl_cmpexch(P,O,N)	OSAtomicCompareAndSwapPtrBarrier ((void *) (O), (void *) (N), (void **) (P))
 #else
 #if __ppc64__ || __x86_64__ || __aarch64__
-#define hb_atomic_ptr_impl_cmpexch(P,O,N)	OSAtomicCompareAndSwap64Barrier ((int64_t) (O), (int64_t) (N), (int64_t*) (P))
+#define hb_atomic_ptr_impl_cmpexch(P,O,N)	OSAtomicCompareAndSwap64Barrier ((int64_t) (void *) (O), (int64_t) (void *) (N), (int64_t*) (P))
 #else
-#define hb_atomic_ptr_impl_cmpexch(P,O,N)	OSAtomicCompareAndSwap32Barrier ((int32_t) (O), (int32_t) (N), (int32_t*) (P))
+#define hb_atomic_ptr_impl_cmpexch(P,O,N)	OSAtomicCompareAndSwap32Barrier ((int32_t) (void *) (O), (int32_t) (void *) (N), (int32_t*) (P))
 #endif
 #endif