diff --git a/bucket/mdbook.json b/bucket/mdbook.json
index 761731a7fc..e6aea4ffcb 100644
--- a/bucket/mdbook.json
+++ b/bucket/mdbook.json
@@ -1,12 +1,12 @@
 {
-    "version": "0.4.25",
+    "version": "0.4.27",
     "description": "Create a book from markdown files.",
     "homepage": "https://github.com/rust-lang/mdBook",
     "license": "MPL-2.0",
     "architecture": {
         "64bit": {
-            "url": "https://github.com/rust-lang/mdBook/releases/download/v0.4.25/mdbook-v0.4.25-x86_64-pc-windows-msvc.zip",
-            "hash": "771e5aa0bffbb475a05f8fa1889550475672fbbec229bc1cfa85e16c3c8852c8"
+            "url": "https://github.com/rust-lang/mdBook/releases/download/v0.4.27/mdbook-v0.4.27-x86_64-pc-windows-msvc.zip",
+            "hash": "18c7eea09bee53f539a11ec965547147afc2083c4cac22563b724aecf57b57bb"
         }
     },
     "bin": "mdbook.exe",