diff --git a/src/flb_http_client_http1.c b/src/flb_http_client_http1.c
index e09950c70fb..cbc4df2155c 100644
--- a/src/flb_http_client_http1.c
+++ b/src/flb_http_client_http1.c
@@ -526,6 +526,9 @@ static int compose_request_line(cfl_sds_t *output_buffer,
     else if (request->protocol_version == HTTP_PROTOCOL_VERSION_09) {
         protocol_version_string = "";
     }
+    else {
+        return -1;
+    }
 
     method_name = flb_http_get_method_string_from_id(request->method);