diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 24fd363..a2b3217 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,17 +19,17 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout current branch
-        uses: actions/checkout@v2
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
         with:
           fetch-depth: 0
 
       - name: Setup Java and Scala
-        uses: olafurpg/setup-scala@v10
+        uses: olafurpg/setup-scala@32ffa16635ff8f19cc21ea253a987f0fdf29844c
         with:
           java-version: adopt@1.8
 
       - name: Cache sbt
-        uses: actions/cache@v2
+        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
         with:
           path: |
             ~/.sbt