diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 8570224..79ea1f5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -6,7 +6,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     container:
-      image: kunitoki/android-ndk-r21
+      image: kunitoki/android-ndk-r21@sha256:ce5aed19936a1f3c99fce2f1135c055248c0faa2f5a930c68e36e81317db4550
     steps:
     - uses: actions/checkout@v2
       with: