diff --git a/.github/workflows/linter.yml b/.github/workflows/linter.yml
index 34b91e644..2619c5b3d 100644
--- a/.github/workflows/linter.yml
+++ b/.github/workflows/linter.yml
@@ -48,7 +48,7 @@ jobs:
         id: changed-files
         run: |
           git fetch origin master
-          BASE_SHA=$(git merge-base origin/master $GITHUB_SHA)
+          $BASE_SHA=$(git merge-base origin/master $GITHUB_SHA)
           CHANGED_FILES=$(git diff --name-only $BASE_SHA $GITHUB_SHA)
           echo "CHANGED_FILES=$CHANGED_FILES" >> $GITHUB_ENV