diff --git a/README.md b/README.md
index df036dd..9fa5c4a 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,7 @@ This action slug and expose some github variables.
 | - | - |
 | GITHUB_REF | GITHUB_REF_SLUG |
 | GITHUB_HEAD_REF | GITHUB_HEAD_REF_SLUG |
+| GITHUB_BASE_REF | GITHUB_BASE_REF_SLUG |
 
 ## Example usage
 
diff --git a/entrypoint.sh b/entrypoint.sh
index d279890..31cd1ab 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -9,3 +9,4 @@ slug_ref() {
 
 echo ::set-env name=GITHUB_REF_SLUG::$(slug_ref $GITHUB_REF)
 echo ::set-env name=GITHUB_HEAD_REF_SLUG::$(slug_ref $GITHUB_HEAD_REF)
+echo ::set-env name=GITHUB_BASE_REF_SLUG::$(slug_ref $GITHUB_BASE_REF)