diff --git a/dist/index.js b/dist/index.js
index d6049ba..3ca3892 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -2079,7 +2079,7 @@ try {
         GITHUB_REF: process.env.GITHUB_REF,
         GITHUB_REPOSITORY: process.env.GITHUB_REPOSITORY,
         GITHUB_SHA: process.env.GITHUB_SHA,
-        GITHUB_HEAD_REF: process.env.GITHUB_HEAD_REF
+        GITHUB_HEAD_REF: process.env.GITHUB_HEAD_REF || ''
       };
 
       const execArgs = ["codecov.sh"];
diff --git a/index.js b/index.js
index d43200f..d2b8e0f 100644
--- a/index.js
+++ b/index.js
@@ -56,7 +56,7 @@ try {
         GITHUB_REF: process.env.GITHUB_REF,
         GITHUB_REPOSITORY: process.env.GITHUB_REPOSITORY,
         GITHUB_SHA: process.env.GITHUB_SHA,
-        GITHUB_HEAD_REF: process.env.GITHUB_HEAD_REF
+        GITHUB_HEAD_REF: process.env.GITHUB_HEAD_REF || ''
       };
 
       const execArgs = ["codecov.sh"];