diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
index ec3e264a73..fbe33ad87e 100644
--- a/src/backend/utils/mmgr/aset.c
+++ b/src/backend/utils/mmgr/aset.c
@@ -150,11 +150,13 @@ typedef AllocSetContext *AllocSet;
  */
 typedef struct AllocBlockData
 {
-	AllocSet	aset;			/* aset that owns this block */
 	AllocBlock	prev;			/* prev block in aset's blocks list, if any */
 	AllocBlock	next;			/* next block in aset's blocks list, if any */
 	char	   *freeptr;		/* start of free space in this block */
 	char	   *endptr;			/* end of space in this block */
+#ifdef MEMORY_CONTEXT_CHECKING
+	AllocSet	aset;			/* aset that owns this block */
+#endif
 }			AllocBlockData;
 
 /*
@@ -485,11 +487,13 @@ AllocSetContextCreateInternal(MemoryContext parent,
 
 	/* Fill in the initial block's block header */
 	block = (AllocBlock) (((char *) set) + MAXALIGN(sizeof(AllocSetContext)));
-	block->aset = set;
 	block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
 	block->endptr = ((char *) set) + firstBlockSize;
 	block->prev = NULL;
 	block->next = NULL;
+#ifdef MEMORY_CONTEXT_CHECKING
+	block->aset = set;
+#endif
 
 	/* Mark unallocated space NOACCESS; leave the block header alone. */
 	VALGRIND_MAKE_MEM_NOACCESS(block->freeptr, block->endptr - block->freeptr);
@@ -743,8 +747,10 @@ AllocSetAlloc(MemoryContext context, Size size)
 
 		context->mem_allocated += blksize;
 
-		block->aset = set;
 		block->freeptr = block->endptr = ((char *) block) + blksize;
+#ifdef MEMORY_CONTEXT_CHECKING
+		block->aset = set;
+#endif
 
 		chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
 		chunk->aset = set;
@@ -936,9 +942,11 @@ AllocSetAlloc(MemoryContext context, Size size)
 
 		context->mem_allocated += blksize;
 
-		block->aset = set;
 		block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
 		block->endptr = ((char *) block) + blksize;
+#ifdef MEMORY_CONTEXT_CHECKING
+		block->aset = set;
+#endif
 
 		/* Mark unallocated space NOACCESS. */
 		VALGRIND_MAKE_MEM_NOACCESS(block->freeptr,
@@ -1019,8 +1027,10 @@ AllocSetFree(MemoryContext context, void *pointer)
 		 * reference the correct aset, and freeptr and endptr should point
 		 * just past the chunk.
 		 */
-		if (block->aset != set ||
-			block->freeptr != block->endptr ||
+		if (block->freeptr != block->endptr ||
+#ifdef MEMORY_CONTEXT_CHECKING
+			block->aset != set ||
+#endif
 			block->freeptr != ((char *) block) +
 			(chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
 			elog(ERROR, "could not find block containing chunk %p", chunk);
@@ -1108,8 +1118,10 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
 		 * reference the correct aset, and freeptr and endptr should point
 		 * just past the chunk.
 		 */
-		if (block->aset != set ||
-			block->freeptr != block->endptr ||
+		if (block->freeptr != block->endptr ||
+#ifdef MEMORY_CONTEXT_CHECKING
+			block->aset != set ||
+#endif
 			block->freeptr != ((char *) block) +
 			(oldsize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
 			elog(ERROR, "could not find block containing chunk %p", chunk);