diff --git a/source/winbindd/idmap_cache.c b/source/winbindd/idmap_cache.c
index 8bf797f9527..eaff30c4e11 100644
--- a/source/winbindd/idmap_cache.c
+++ b/source/winbindd/idmap_cache.c
@@ -25,6 +25,7 @@
 
 #define TIMEOUT_LEN 12
 #define IDMAP_CACHE_DATA_FMT	"%12u/%s"
+#define IDMAP_READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
 
 struct idmap_cache_ctx {
 	TDB_CONTEXT *tdb;