diff --git a/bucket/coq.json b/bucket/coq.json
index b00bee8ed5..641ee01d3d 100644
--- a/bucket/coq.json
+++ b/bucket/coq.json
@@ -28,7 +28,7 @@
         ]
     ],
     "env_set": {
-        "COQBIN": "bin"
+        "COQBIN": "$dir\\bin"
     },
     "checkver": {
         "url": "https://api.github.com/repositories/212040108/releases/latest",