diff --git a/action.yml b/action.yml
index 2536c19..701fc8e 100644
--- a/action.yml
+++ b/action.yml
@@ -75,11 +75,11 @@ inputs:
   github-api-url:
     description: 'configure github API URL. Default `https://api.github.com`'
     required: false
-    default: ''
+    default: ${{ github.api_url }}
   github-graphql-url:
     description: 'configure github GraphQL URL. Default `https://api.github.com`'
     required: false
-    default: ''
+    default: ${{ github.graphql_url }}
   repo-url:
     description: 'configure github repository URL. Default `process.env.GITHUB_REPOSITORY`'
     required: false
diff --git a/index.js b/index.js
index bc50326..0ca70ef 100644
--- a/index.js
+++ b/index.js
@@ -18,7 +18,7 @@ function getGitHubInput () {
     defaultBranch: core.getInput('default-branch') || undefined,
     repoUrl: core.getInput('repo-url') || process.env.GITHUB_REPOSITORY,
     apiUrl: core.getInput('github-api-url') || GITHUB_API_URL,
-    graphqlUrl: core.getInput('github-graphql-url') || GITHUB_GRAPHQL_URL,
+    graphqlUrl: (core.getInput('github-graphql-url') || '').replace(/\/graphql$/, '') || GITHUB_GRAPHQL_URL,
     token: core.getInput('token', { required: true })
   }
 }