diff --git a/src/ucl_parser.c b/src/ucl_parser.c
index b035c3f..04014af 100644
--- a/src/ucl_parser.c
+++ b/src/ucl_parser.c
@@ -349,6 +349,8 @@ ucl_check_variable_safe (struct ucl_parser *parser, const char *ptr, size_t rema
 		if (parser->var_handler (ptr, remain, &dst, &dstlen, &need_free,
 				parser->var_data)) {
 			*found = true;
+			*out_len = dstlen;
+
 			if (need_free) {
 				free (dst);
 			}