diff --git a/lib/fko_encode.c b/lib/fko_encode.c
index c92d421..5775943 100644
--- a/lib/fko_encode.c
+++ b/lib/fko_encode.c
@@ -59,6 +59,8 @@ append_b64(char* tbuf, char *str)
 
     free(bs);
 
+    tbuf[1] = '=';
+
     return(FKO_SUCCESS);
 }