diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index f0f8d4259c..25f7327a82 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -58,6 +58,7 @@
 #include "utils/resowner.h"
 #include "utils/timestamp.h"
 
+#include "tcop/tcopprot.h"
 
 /* Note: these two macros only work on shared buffers, not local ones! */
 #define BufHdrGetBlock(bufHdr)	((Block) (BufferBlocks + ((Size) (bufHdr)->buf_id) * BLCKSZ))
@@ -5041,6 +5042,8 @@ ConditionalLockBufferForCleanup(Buffer buffer)
 
 	Assert(BufferIsValid(buffer));
 
+if (debug_query_string && (strcmp(debug_query_string, "VACUUM ANALYZE tenk2;") == 0) && (rand() % 100 == 0))
+{ elog(LOG, "!!!ConditionalLockBufferForCleanup() returning false"); return false; }
 	if (BufferIsLocal(buffer))
 	{
 		refcount = LocalRefCount[-buffer - 1];