diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index e1e6240..6640172 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1548,7 +1548,6 @@ UnpinBuffer(volatile BufferDesc *buf, bool fixOwner)
 			/* we just released the last pin other than the waiter's */
 			int			wait_backend_pid = buf->wait_backend_pid;
 
-			buf->flags &= ~BM_PIN_COUNT_WAITER;
 			UnlockBufHdr(buf);
 			ProcSendSignal(wait_backend_pid);
 		}
@@ -3273,6 +3272,13 @@ LockBufferForCleanup(Buffer buffer)
 		else
 			ProcWaitForSignal();
 
+		/*
+		 * Clear the flag unconditionally here, because otherwise a spurious
+		 * signal (which is allowed) could make it look like an error.
+		 */
+		LockBufHdr(bufHdr);
+		bufHdr->flags &= ~BM_PIN_COUNT_WAITER;
+		UnlockBufHdr(bufHdr);
 		PinCountWaitBuf = NULL;
 		/* Loop back and try again */
 	}