diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index 185d6e5ee..59ce97b9e 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -36,7 +36,7 @@ jobs:
           path: screencap.png
 
   unit_test_and_release:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     steps:
 
       - name: checkout
diff --git a/custom/.gitignore b/custom/.gitignore
index 796b96d1c..c00d922bb 100644
--- a/custom/.gitignore
+++ b/custom/.gitignore
@@ -1 +1,2 @@
 /build
+jacoco.exec