diff --git a/action.yml b/action.yml
index 33c973d..0df1c55 100644
--- a/action.yml
+++ b/action.yml
@@ -50,6 +50,7 @@ runs:
         echo "${{ github.token }}" | ko login ghcr.io --username "dummy" --password-stdin
 
         # Set KO_DOCKER_REPO for future steps.
-        echo "KO_DOCKER_REPO=ghcr.io/${{ github.repository }}"
-        echo "KO_DOCKER_REPO=ghcr.io/${{ github.repository }}" >> $GITHUB_ENV
+        GITHUB_REPOSITORY="${{ github.repository }}"
+        echo "KO_DOCKER_REPO=ghcr.io/${GITHUB_REPOSITORY,,}"
+        echo "KO_DOCKER_REPO=ghcr.io/${GITHUB_REPOSITORY,,}" >> $GITHUB_ENV
       fi