diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c
index ae9d6f3..6d18abb 100644
--- a/src/core/ngx_slab.c
+++ b/src/core/ngx_slab.c
@@ -440,7 +440,8 @@
         n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift;
         m = (uintptr_t) 1 << (n & (sizeof(uintptr_t) * 8 - 1));
         n /= (sizeof(uintptr_t) * 8);
-        bitmap = (uintptr_t *) ((uintptr_t) p & ~(ngx_pagesize - 1));
+        bitmap = (uintptr_t *)
+                             ((uintptr_t) p & ~((uintptr_t) ngx_pagesize - 1));
 
         if (bitmap[n] & m) {