diff --git a/bucket/dafny.json b/bucket/dafny.json
index a11dfbde93..25ee43cdae 100644
--- a/bucket/dafny.json
+++ b/bucket/dafny.json
@@ -1,12 +1,12 @@
 {
-    "version": "4.9.0",
+    "version": "4.9.1",
     "description": "A programming language with a program verifier",
     "homepage": "https://dafny-lang.github.io/dafny/",
     "license": "MIT",
     "architecture": {
         "64bit": {
-            "url": "https://github.com/dafny-lang/dafny/releases/download/v4.9.0/dafny-4.9.0-x64-windows-2019.zip",
-            "hash": "c02aa642d9a37b5c1440c8c3fae9f6285ee0fbcd0088572fb513fb51ef1506f6",
+            "url": "https://github.com/dafny-lang/dafny/releases/download/v4.9.1/dafny-4.9.1-x64-windows-2019.zip",
+            "hash": "42d2e013c18bb73c4dea3eab42dc91240991e70295d247e314021b4baddb43c8",
             "extract_dir": "dafny"
         }
     },