diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 8092381ae5c..193c3dadbf2 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -3902,12 +3902,31 @@ RemoveTempRelationsCallback(int code, Datum arg)
 
 /*
  * Remove all temp tables from the temporary namespace.
+ *
+ * If we haven't set up one yet, but one exists from a previous crashed
+ * backend, clean that one; but only do this once in a session's life.
  */
 void
 ResetTempTableNamespace(void)
 {
+	static bool	TempNamespaceCleaned = false;
+
 	if (OidIsValid(myTempNamespace))
 		RemoveTempRelations(myTempNamespace);
+	else if (MyBackendId != InvalidBackendId && !RecoveryInProgress() &&
+			 !TempNamespaceCleaned)
+	{
+		char		namespaceName[NAMEDATALEN];
+		Oid			namespaceId;
+
+		snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
+				 MyBackendId);
+		namespaceId = get_namespace_oid(namespaceName, true);
+		if (OidIsValid(namespaceId))
+			RemoveTempRelations(namespaceId);
+	}
+
+	TempNamespaceCleaned = true;
 }