diff --git a/lib/fko_encode.c b/lib/fko_encode.c
index c92d421..e8909d1 100644
--- a/lib/fko_encode.c
+++ b/lib/fko_encode.c
@@ -105,7 +105,7 @@ fko_encode_spa_data(fko_ctx_t ctx)
 
     /* Add the base64-encoded username.
     */
-    strlcat(tbuf, ":", FKO_ENCODE_TMP_BUF_SIZE);
+    strlcat(tbuf, "::", FKO_ENCODE_TMP_BUF_SIZE);
     if((res = append_b64(tbuf, ctx->username)) != FKO_SUCCESS)
     {
         free(tbuf);