diff --git a/mm/mm_gran/mm_graninit.c b/mm/mm_gran/mm_graninit.c
index 777889de15f..0ae0e4cf8b5 100644
--- a/mm/mm_gran/mm_graninit.c
+++ b/mm/mm_gran/mm_graninit.c
@@ -99,7 +99,7 @@ GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize,
   FAR struct gran_s *priv;
   uintptr_t          heapend;
   uintptr_t          alignedstart;
-  unsigned int       mask;
+  size_t             mask;
   unsigned int       alignedsize;
   unsigned int       ngranules;