diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 74d9dae..ea09cf3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -53,7 +53,7 @@ jobs:
         # The action tag IS the toolchain version installed; @1.88 pins MSRV.
         # (Dependabot bumped this to @1.100 in #17, which tries to install a
         # non-existent rust 1.100.0 — revert to the real MSRV.)
-        uses: dtolnay/rust-toolchain@1.88
+        uses: dtolnay/rust-toolchain@1.100
 
       - name: Cache cargo
         uses: Swatinem/rust-cache@v2