diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a4c3ffc..5d3a819 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -22,7 +22,7 @@ jobs:
       - name: Build executables
         run: |
           for file in $(cat files.txt); do
-            g++ -o $file-${{ github.ref_name[0:4] }} $file
+            g++ -o $file-${{ github.ref_name.substring(0, 4) }} $file
           done
 
   release:
@@ -35,10 +35,10 @@ jobs:
       - name: Create release
         uses: actions/create-release@v1
         with:
-          tag_name: ${{ github.ref_name[0:4] }}
-          release_name: Release ${{ github.ref_name[0:4] }}
+          tag_name: ${{ github.ref_name.substring(0, 4) }}
+          release_name: Release ${{ github.ref_name.substring(0, 4) }}
           body: |
-            This is the release ${{ github.ref_name[0:4] }}.
+            This is the release ${{ github.ref_name.substring(0, 4) }}.
 
           draft: false
           prerelease: false
@@ -48,4 +48,4 @@ jobs:
         with:
           name: executables
           path: |
-            $(cat files.txt)-${{ github.ref_name[0:4] }}
+            $(cat files.txt)-${{ github.ref_name.substring(0, 4) }}