diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index c2c445dbf4..b773a76049 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -41,6 +41,7 @@
 
 #include "postgres.h"
 
+#include "commands/tablespace.h"
 #include "executor/instrument.h"
 #include "miscadmin.h"
 #include "pgstat.h"
@@ -185,6 +186,17 @@ BufFileCreateTemp(bool interXact)
 	BufFile    *file;
 	File		pfile;
 
+	/*
+	 * Ensure that temp tablespaces are set up for OpenTemporaryFile to use.
+	 * Possibly the caller will have done this already, but it seems useful to
+	 * double-check here.  Failure to do this at all would result in the temp
+	 * files always getting placed in the default tablespace, which is a
+	 * pretty hard-to-detect bug.  Callers may prefer to do it earlier if they
+	 * want to be sure that any required catalog access is done in some other
+	 * resource context.
+	 */
+	PrepareTempTablespaces();
+
 	pfile = OpenTemporaryFile(interXact);
 	Assert(pfile >= 0);