diff --git a/mm/mm_heap/mm.h b/mm/mm_heap/mm.h
index 65ee07cc566..9e908a38c3a 100644
--- a/mm/mm_heap/mm.h
+++ b/mm/mm_heap/mm.h
@@ -114,6 +114,7 @@
  */
 
 #define MM_ALLOC_BIT     0x1
+#define MM_MASK_BIT      MM_ALLOC_BIT
 #ifdef CONFIG_MM_SMALL
 # define MMSIZE_MAX      UINT16_MAX
 #else
diff --git a/mm/mm_heap/mm_foreach.c b/mm/mm_heap/mm_foreach.c
index 70cf1579c00..9c86fd2dbb6 100644
--- a/mm/mm_heap/mm_foreach.c
+++ b/mm/mm_heap/mm_foreach.c
@@ -86,7 +86,7 @@ void mm_foreach(FAR struct mm_heap_s *heap, mmchunk_handler_t handler,
           handler(node, arg);
 
           DEBUGASSERT(prev == NULL ||
-                      prev->size == (node->preceding & ~MM_ALLOC_BIT));
+                      prev->size == (node->preceding & ~MM_MASK_BIT));
           prev = node;
         }
 
diff --git a/mm/mm_heap/mm_free.c b/mm/mm_heap/mm_free.c
index dcb89fe05f2..d7d75d574b5 100644
--- a/mm/mm_heap/mm_free.c
+++ b/mm/mm_heap/mm_free.c
@@ -107,12 +107,12 @@ void mm_free(FAR struct mm_heap_s *heap, FAR void *mem)
 
   DEBUGASSERT(node->preceding & MM_ALLOC_BIT);
 
-  node->preceding &= ~MM_ALLOC_BIT;
+  node->preceding &= ~MM_MASK_BIT;
 
   /* Check if the following node is free and, if so, merge it */
 
   next = (FAR struct mm_freenode_s *)((FAR char *)node + node->size);
-  DEBUGASSERT((next->preceding & ~MM_ALLOC_BIT) == node->size);
+  DEBUGASSERT((next->preceding & ~MM_MASK_BIT) == node->size);
   if ((next->preceding & MM_ALLOC_BIT) == 0)
     {
       FAR struct mm_allocnode_s *andbeyond;
@@ -140,7 +140,7 @@ void mm_free(FAR struct mm_heap_s *heap, FAR void *mem)
 
       node->size          += next->size;
       andbeyond->preceding = node->size |
-                             (andbeyond->preceding & MM_ALLOC_BIT);
+                             (andbeyond->preceding & MM_MASK_BIT);
       next                 = (FAR struct mm_freenode_s *)andbeyond;
     }
 
@@ -149,7 +149,7 @@ void mm_free(FAR struct mm_heap_s *heap, FAR void *mem)
    */
 
   prev = (FAR struct mm_freenode_s *)((FAR char *)node - node->preceding);
-  DEBUGASSERT((node->preceding & ~MM_ALLOC_BIT) == prev->size);
+  DEBUGASSERT((node->preceding & ~MM_MASK_BIT) == prev->size);
   if ((prev->preceding & MM_ALLOC_BIT) == 0)
     {
       /* Remove the node.  There must be a predecessor, but there may
@@ -166,7 +166,7 @@ void mm_free(FAR struct mm_heap_s *heap, FAR void *mem)
       /* Then merge the two chunks */
 
       prev->size     += node->size;
-      next->preceding = prev->size | (next->preceding & MM_ALLOC_BIT);
+      next->preceding = prev->size | (next->preceding & MM_MASK_BIT);
       node            = prev;
     }
 
diff --git a/mm/mm_heap/mm_malloc.c b/mm/mm_heap/mm_malloc.c
index c1d52b23c98..0f1bb578085 100644
--- a/mm/mm_heap/mm_malloc.c
+++ b/mm/mm_heap/mm_malloc.c
@@ -221,7 +221,7 @@ FAR void *mm_malloc(FAR struct mm_heap_s *heap, size_t size)
            * the allocated flag.
            */
 
-          next->preceding = remaining | (next->preceding & MM_ALLOC_BIT);
+          next->preceding = remaining | (next->preceding & MM_MASK_BIT);
 
           /* Add the remainder back into the nodelist */
 
diff --git a/mm/mm_heap/mm_memalign.c b/mm/mm_heap/mm_memalign.c
index 4608aa18c69..8e814fdf912 100644
--- a/mm/mm_heap/mm_memalign.c
+++ b/mm/mm_heap/mm_memalign.c
@@ -184,7 +184,7 @@ FAR void *mm_memalign(FAR struct mm_heap_s *heap, size_t alignment,
       /* Reduce the size of the original chunk and mark it not allocated, */
 
       node->size = precedingsize;
-      node->preceding &= ~MM_ALLOC_BIT;
+      node->preceding &= ~MM_MASK_BIT;
 
       /* Fix the preceding size of the next node */
 
diff --git a/mm/mm_heap/mm_realloc.c b/mm/mm_heap/mm_realloc.c
index 11a937a1a21..e45365fd1cd 100644
--- a/mm/mm_heap/mm_realloc.c
+++ b/mm/mm_heap/mm_realloc.c
@@ -151,7 +151,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
     }
 
   prev = (FAR struct mm_freenode_s *)
-    ((FAR char *)oldnode - (oldnode->preceding & ~MM_ALLOC_BIT));
+    ((FAR char *)oldnode - (oldnode->preceding & ~MM_MASK_BIT));
   if ((prev->preceding & MM_ALLOC_BIT) == 0)
     {
       prevsize = prev->size;
@@ -253,7 +253,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
               newnode->size      = oldsize + takeprev;
               newnode->preceding = prev->size | MM_ALLOC_BIT;
               next->preceding    = newnode->size |
-                                   (next->preceding & MM_ALLOC_BIT);
+                                   (next->preceding & MM_MASK_BIT);
 
               /* Return the previous free node to the nodelist
                * (with the new size)
@@ -268,7 +268,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
               newnode->size      += oldsize;
               newnode->preceding |= MM_ALLOC_BIT;
               next->preceding     = newnode->size |
-                                    (next->preceding & MM_ALLOC_BIT);
+                                    (next->preceding & MM_MASK_BIT);
             }
 
           newmem = (FAR void *)((FAR char *)newnode + SIZEOF_MM_ALLOCNODE);
@@ -321,7 +321,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
               DEBUGASSERT(newnode->size >= SIZEOF_MM_FREENODE);
               newnode->preceding   = oldnode->size;
               andbeyond->preceding = newnode->size |
-                                     (andbeyond->preceding & MM_ALLOC_BIT);
+                                     (andbeyond->preceding & MM_MASK_BIT);
 
               /* Add the new free node to the nodelist (with the new size) */
 
@@ -332,7 +332,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
               /* Yes, just update some pointers. */
 
               andbeyond->preceding = oldnode->size |
-                                     (andbeyond->preceding & MM_ALLOC_BIT);
+                                     (andbeyond->preceding & MM_MASK_BIT);
             }
         }
 
diff --git a/mm/mm_heap/mm_shrinkchunk.c b/mm/mm_heap/mm_shrinkchunk.c
index 1743e546871..5f57519440a 100644
--- a/mm/mm_heap/mm_shrinkchunk.c
+++ b/mm/mm_heap/mm_shrinkchunk.c
@@ -95,7 +95,7 @@ void  mm_shrinkchunk(FAR struct mm_heap_s *heap,
       newnode->preceding   = size;
       node->size           = size;
       andbeyond->preceding = newnode->size |
-                             (andbeyond->preceding & MM_ALLOC_BIT);
+                             (andbeyond->preceding & MM_MASK_BIT);
 
       /* Add the new node to the freenodelist */
 
@@ -121,7 +121,8 @@ void  mm_shrinkchunk(FAR struct mm_heap_s *heap,
       newnode->size        = node->size - size;
       newnode->preceding   = size;
       node->size           = size;
-      next->preceding      = newnode->size | MM_ALLOC_BIT;
+      next->preceding      = newnode->size |
+                             (next->preceding & MM_MASK_BIT);
 
       /* Add the new node to the freenodelist */