diff --git a/src/microhttpd/memorypool.c b/src/microhttpd/memorypool.c
index 12a22f22..5f532b83 100644
--- a/src/microhttpd/memorypool.c
+++ b/src/microhttpd/memorypool.c
@@ -54,7 +54,7 @@
 /**
  * Round up 'n' to a multiple of ALIGN_SIZE.
  */
-#define ROUND_TO_ALIGN(n) (((n)+(ALIGN_SIZE-1)) & (~(ALIGN_SIZE-1)))
+#define ROUND_TO_ALIGN(n) (((n)+(ALIGN_SIZE-1)) / (ALIGN_SIZE) * (ALIGN_SIZE))
 
 
 /**