diff --git a/mm/mm_heap/mm_initialize.c b/mm/mm_heap/mm_initialize.c
index e49e249ffad..b30b5016335 100644
--- a/mm/mm_heap/mm_initialize.c
+++ b/mm/mm_heap/mm_initialize.c
@@ -92,7 +92,7 @@ void mm_addregion(FAR struct mm_heap_s *heap, FAR void *heapstart,
   heapend  = MM_ALIGN_DOWN((uintptr_t)heapstart + (uintptr_t)heapsize);
   heapsize = heapend - heapbase;
 
-  minfo("Region %d: base=%p size=%u\n", IDX + 1, heapstart, heapsize);
+  minfo("Region %d: base=%p size=%zu\n", IDX + 1, heapstart, heapsize);
 
   /* Add the size of this region to the total size of the heap */
 
@@ -157,7 +157,7 @@ void mm_initialize(FAR struct mm_heap_s *heap, FAR void *heapstart,
 {
   int i;
 
-  minfo("Heap: start=%p size=%u\n", heapstart, heapsize);
+  minfo("Heap: start=%p size=%zu\n", heapstart, heapsize);
 
   /* The following two lines have cause problems for some older ZiLog
    * compilers in the past (but not the more recent).  Life is easier if we