diff --git a/.github/workflows/sdk.yaml b/.github/workflows/sdk.yaml
index 53613534e..93027a77c 100644
--- a/.github/workflows/sdk.yaml
+++ b/.github/workflows/sdk.yaml
@@ -33,6 +33,7 @@ jobs:
             path: seL4
       - name: Install SDK dependencies
         run: |
+          rustup install 1.91.0
           rustup target add x86_64-unknown-linux-musl
           rustup component add rust-src --toolchain stable-x86_64-unknown-linux-gnu
           rustup target add aarch64-unknown-linux-musl
diff --git a/flake.lock b/flake.lock
index bc19ab9f2..997a03c7d 100644
--- a/flake.lock
+++ b/flake.lock
@@ -45,11 +45,11 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1753671061,
-        "narHash": "sha256-IU4eBWfe9h2QejJYST+EAlhg8a1H6mh9gbcmWgZ2/mQ=",
+        "lastModified": 1762223900,
+        "narHash": "sha256-caxpESVH71mdrdihYvQZ9rTZPZqW0GyEG9un7MgpyRM=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "40065d17ee4dbec3ded8ca61236132aede843fab",
+        "rev": "cfe1598d69a42a5edb204770e71b8df77efef2c3",
         "type": "github"
       },
       "original": {
diff --git a/initialiser/support/targets/aarch64-sel4-minimal.json b/initialiser/support/targets/aarch64-sel4-minimal.json
index 46fc21aa8..96c14fa07 100644
--- a/initialiser/support/targets/aarch64-sel4-minimal.json
+++ b/initialiser/support/targets/aarch64-sel4-minimal.json
@@ -30,5 +30,5 @@
     "kcfi",
     "kernel-address"
   ],
-  "target-pointer-width": "64"
+  "target-pointer-width": 64
 }
diff --git a/initialiser/support/targets/riscv64imac-sel4-minimal.json b/initialiser/support/targets/riscv64imac-sel4-minimal.json
index 8697c8c59..6e6803eda 100644
--- a/initialiser/support/targets/riscv64imac-sel4-minimal.json
+++ b/initialiser/support/targets/riscv64imac-sel4-minimal.json
@@ -24,5 +24,5 @@
     "shadow-call-stack",
     "kernel-address"
   ],
-  "target-pointer-width": "64"
+  "target-pointer-width": 64
 }
diff --git a/initialiser/support/targets/x86_64-sel4-minimal.json b/initialiser/support/targets/x86_64-sel4-minimal.json
index c09af2c79..6266d15e8 100644
--- a/initialiser/support/targets/x86_64-sel4-minimal.json
+++ b/initialiser/support/targets/x86_64-sel4-minimal.json
@@ -28,5 +28,5 @@
     "kcfi",
     "kernel-address"
   ],
-  "target-pointer-width": "64"
+  "target-pointer-width": 64
 }
diff --git a/tool/microkit/Cargo.toml b/tool/microkit/Cargo.toml
index ea6b0ee34..78715461f 100644
--- a/tool/microkit/Cargo.toml
+++ b/tool/microkit/Cargo.toml
@@ -8,7 +8,7 @@
 name = "microkit-tool"
 version = "2.0.1-dev"
 edition = "2021"
-rust-version = "1.88.0"
+rust-version = "1.91.0"
 
 [[bin]]
 name = "microkit"