diff --git a/include/Support/hash_map b/include/Support/hash_map
index 68ee596a855..dc905da4101 100644
--- a/include/Support/hash_map
+++ b/include/Support/hash_map
@@ -37,6 +37,7 @@
 #endif
 
 using HASH_NAMESPACE::hash_map;
+using HASH_NAMESPACE::hash_multimap;
 using HASH_NAMESPACE::hash;
 
 #include <Support/HashExtras.h>