diff --git a/src/unit-test-coverage/ut-stubs/src/libc-stdlib-stubs.c b/src/unit-test-coverage/ut-stubs/src/libc-stdlib-stubs.c
index 9b22b7188..8e042dcae 100644
--- a/src/unit-test-coverage/ut-stubs/src/libc-stdlib-stubs.c
+++ b/src/unit-test-coverage/ut-stubs/src/libc-stdlib-stubs.c
@@ -150,7 +150,7 @@ void *OCS_malloc(size_t sz)
         return NULL;
     }
 
-    NextSize  = (NextSize + MPOOL_ALIGN - 1) & ~((size_t)MPOOL_ALIGN);
+    NextSize  = (NextSize + MPOOL_ALIGN - 1) & ~((size_t)MPOOL_ALIGN - 1);
     NextBlock = Rec->BlockAddr + MPOOL_ALIGN;
     Rec->BlockAddr += NextSize;
     Rec->Size += NextSize;