diff --git a/bucket/mdbook.json b/bucket/mdbook.json
index efac03d9d1..ba1fa1a8fa 100644
--- a/bucket/mdbook.json
+++ b/bucket/mdbook.json
@@ -1,12 +1,12 @@
 {
-    "version": "0.4.19",
+    "version": "0.4.20",
     "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/v0.4.19/mdbook-v0.4.19-x86_64-pc-windows-msvc.zip",
-            "hash": "48822e82cee0ae2961318f3c820b001e8deb8819491593ace725d03d75cd3825"
+            "url": "https://github.com/rust-lang/mdBook/releases/download/v0.4.20/mdbook-v0.4.20-x86_64-pc-windows-msvc.zip",
+            "hash": "8befdc124c4d39c7a5bf715c68fdd5ae48b731ef4d987bdb823ec91d6a8ac828"
         }
     },
     "bin": "mdbook.exe",