diff --git a/.forgejo/workflows/build.yml b/.forgejo/workflows/build.yml
index a2e5c5e..636aff9 100644
--- a/.forgejo/workflows/build.yml
+++ b/.forgejo/workflows/build.yml
@@ -35,7 +35,14 @@ jobs:
           SONAR_PROJECT_KEY: ${{ secrets.SONAR_PROJECT_KEY }}
         run: |
           HOST_URL=${SONAR_HOST_URL:?SONAR_HOST_URL secret not set}
-          PROJECT_KEY=${SONAR_PROJECT_KEY:?SONAR_PROJECT_KEY secret not set}
+          PROJECT_KEY=${SONAR_PROJECT_KEY:-}
+          if [ -z "$PROJECT_KEY" ] && [ -f sonar-project.properties ]; then
+            PROJECT_KEY=$(grep -E '^sonar.projectKey=' sonar-project.properties | cut -d= -f2 | tr -d '\r')
+          fi
+          if [ -z "$PROJECT_KEY" ]; then
+            echo "SONAR_PROJECT_KEY secret not set and no sonar-project.properties entry found" >&2
+            exit 1
+          fi
           docker run --rm \
             -e SONAR_HOST_URL="$HOST_URL" \
             -e SONAR_TOKEN="$SONAR_TOKEN" \
@@ -44,7 +51,6 @@ jobs:
             sonarsource/sonar-scanner-cli \
             sonar-scanner \
               -Dsonar.host.url="$HOST_URL" \
-              -Dsonar.token="$SONAR_TOKEN" \
               -Dsonar.projectKey="$PROJECT_KEY" \
               -Dsonar.sources=. \
               -Dsonar.scm.provider=none \