diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index c3e72fb1b967..e2bb3d89b7a4 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -657,7 +657,7 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
 
 	if (RelationUsesLocalBuffers(reln))
 	{
-		/* see comments in ReadBufferExtended */
+		/* see comments in PinBufferForBlock */
 		if (RELATION_IS_OTHER_TEMP(reln))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -794,16 +794,6 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
 {
 	Buffer		buf;
 
-	/*
-	 * Reject attempts to read non-local temporary relations; we would be
-	 * likely to get wrong data since we have no visibility into the owning
-	 * session's local buffers.
-	 */
-	if (RELATION_IS_OTHER_TEMP(reln))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions")));
-
 	/*
 	 * Read the buffer, and update pgstat counters to reflect a cache hit or
 	 * miss.
@@ -1109,6 +1099,18 @@ PinBufferForBlock(Relation rel,
 
 	if (persistence == RELPERSISTENCE_TEMP)
 	{
+		/*
+		 * Reject attempts to read non-local temporary relations; we would be
+		 * likely to get wrong data since we have no visibility into the
+		 * owning session's local buffers.  We don't expect to get here
+		 * without a relcache entry (see ReadBufferWithoutRelcache).
+		 */
+		Assert(rel);
+		if (RELATION_IS_OTHER_TEMP(rel))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot access temporary tables of other sessions")));
+
 		io_context = IOCONTEXT_NORMAL;
 		io_object = IOOBJECT_TEMP_RELATION;
 	}