diff --git a/firebase.json b/firebase.json
index be0cb0cab..1d00a3ec7 100644
--- a/firebase.json
+++ b/firebase.json
@@ -24,6 +24,7 @@
     }
   },
   "functions": {
-    "source": "functions"
+    "source": "functions",
+    "runtime": "nodejs12"
   }
 }