diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 682b1bf..53ea2a1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -157,7 +157,7 @@ jobs:
       with:
         # The prefix cache key, this can be changed to start a new cache manually.
         # default: "v0-rust"
-        prefix-key: ${{ matrix.platform }}
+        prefix-key: ${{ matrix.platform.os }}
         shared-key: ci
         cache-targets: false
     - name: install app dependencies