diff --git a/action.yaml b/action.yaml
index bf17484..0b39365 100644
--- a/action.yaml
+++ b/action.yaml
@@ -5,7 +5,7 @@ inputs:
   gitea_url:
     description: "Base URL of the Gitea instance"
     required: false
-    default: "https://gitea.psi.ch"
+    default: ""
   repository:
     description: "Target repository as owner/repo"
     required: false
@@ -49,54 +49,39 @@ runs:
     - id: create_pr
       name: Create Pull Request
       shell: bash
-      env:
-        INPUT_GITEA_URL: ${{ inputs.gitea_url }}
-        INPUT_REPOSITORY: ${{ inputs.repository }}
-        INPUT_TOKEN: ${{ inputs.token }}
-        INPUT_TITLE: ${{ inputs.title }}
-        INPUT_BODY: ${{ inputs.body }}
-        INPUT_HEAD: ${{ inputs.head }}
-        INPUT_BASE: ${{ inputs.base }}
-        INPUT_ALLOW_EXISTING: ${{ inputs.allow_existing }}
-        GITHUB_REPOSITORY: ${{ github.repository }}
       run: |
         set -euo pipefail
 
-        GITEA_URL="${INPUT_GITEA_URL:-https://gitea.psi.ch}"
-        REPOSITORY="${INPUT_REPOSITORY:-${GITHUB_REPOSITORY}}"
-        HEAD="${INPUT_HEAD}"
-        BASE="${INPUT_BASE:-main}"
-        ALLOW_EXISTING="${INPUT_ALLOW_EXISTING:-true}"
+        GITEA_URL="${{ inputs.gitea_url }}"
+        GITEA_URL="${GITEA_URL:-${{ github.server_url }}}"
+
+        REPOSITORY="${{ inputs.repository }}"
+        REPOSITORY="${REPOSITORY:-${{ github.repository }}}"
+
+        TOKEN="${{ inputs.token }}"
+        TITLE="${{ inputs.title }}"
+        BODY="${{ inputs.body }}"
+        HEAD="${{ inputs.head }}"
+        BASE="${{ inputs.base }}"
+        BASE="${BASE:-main}"
+        ALLOW_EXISTING="${{ inputs.allow_existing }}"
+        ALLOW_EXISTING="${ALLOW_EXISTING:-true}"
 
         if [[ ! "${REPOSITORY}" =~ ^[^/]+/[^/]+$ ]]; then
           echo "::error::repository must be owner/repo, got: ${REPOSITORY}"
           exit 1
         fi
 
-        if [ -z "${INPUT_TOKEN}" ]; then
-          echo "::error::token is required"
-          exit 1
-        fi
-
-        if [ -z "${INPUT_TITLE}" ]; then
-          echo "::error::title is required"
-          exit 1
-        fi
-
-        if [ -z "${HEAD}" ]; then
-          echo "::error::head is required"
-          exit 1
-        fi
 
         API_BASE="${GITEA_URL}/api/v1/repos/${REPOSITORY}"
-        AUTH_HEADER="Authorization: token ${INPUT_TOKEN}"
+        AUTH_HEADER="Authorization: token ${TOKEN}"
 
         echo "::notice::Creating pull request ${REPOSITORY}: ${HEAD} -> ${BASE}"
 
         PAYLOAD="$(
           jq -n \
-            --arg title "${INPUT_TITLE}" \
-            --arg body "${INPUT_BODY}" \
+            --arg title "${TITLE}" \
+            --arg body "${BODY}" \
             --arg head "${HEAD}" \
             --arg base "${BASE}" \
             '{title: $title, body: $body, head: $head, base: $base}'