diff --git a/src/util.c b/src/util.c
index 74a0c76d9fe1870af8066e90887e5bfd51c8c085..222365d2a8a4939c99aabbac191ac72bedea5e2b 100644
--- a/src/util.c
+++ b/src/util.c
@@ -304,6 +304,7 @@ char *util_base64_encode(char *data)
         data += chunk;
         len -= chunk;
     }
+    *out = 0;
 
     return result;
 }