diff --git a/.github/workflows/continuous_integration.yml b/.github/workflows/continuous_integration.yml
index 801b997e..17dedc17 100644
--- a/.github/workflows/continuous_integration.yml
+++ b/.github/workflows/continuous_integration.yml
@@ -16,7 +16,7 @@ jobs:
         os: [macos-latest, ubuntu-latest]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
       - uses: fish-actions/install-fish@v1.1.0
 
       - uses: fish-actions/fisher@v1
@@ -36,7 +36,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - uses: fish-actions/install-fish@v1
 
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - uses: fish-actions/install-fish@v1
 
@@ -57,7 +57,7 @@ jobs:
   prettier:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
       - uses: actionsx/prettier@v2
         with:
           args: --check .