diff --git a/src/backend/utils/mmgr/slab.c b/src/backend/utils/mmgr/slab.c
index a5e140e..c673bc3 100644
--- a/src/backend/utils/mmgr/slab.c
+++ b/src/backend/utils/mmgr/slab.c
@@ -207,7 +207,7 @@ SlabContextCreate(MemoryContext parent,
 
 	/* Make sure the block can store at least one chunk. */
 	if (blockSize - sizeof(SlabBlock) < fullChunkSize)
-		elog(ERROR, "block size %ld for slab is too small for %ld chunks",
+		elog(ERROR, "block size %zu for slab is too small for %zu chunks",
 			 blockSize, chunkSize);
 
 	/* Compute maximum number of chunks per block */
@@ -333,7 +333,7 @@ SlabAlloc(MemoryContext context, Size size)
 
 	/* make sure we only allow correct request size */
 	if (size != slab->chunkSize)
-		elog(ERROR, "unexpected alloc chunk size %ld (expected %ld)",
+		elog(ERROR, "unexpected alloc chunk size %zu (expected %zu)",
 			 size, slab->chunkSize);
 
 	/*