diff --git a/spec.json b/spec.json
index 7a4eed3..d054e0b 100644
--- a/spec.json
+++ b/spec.json
@@ -12,7 +12,7 @@
 	"inputs": {
 		"src": {
 			"type": "git",
-			"value": "https://github.com/illustris/hydra-builds.git",
+			"value": "https://github.com/illustris/hydra-builds.git master",
 			"emailresponsible": false
 		},
 		"nixpkgs": {