diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 15c758db..98d0ece1 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -5,7 +5,7 @@ jobs:
     runs-on: ${{matrix.os}}
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-20.04]
     steps:
       - uses: actions/checkout@v3
         with:
diff --git a/.gitignore b/.gitignore
index 2dccdae6..450e9f3a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,4 +12,5 @@ dist-docs.*/
 *.prof
 *.ps
 *.ser
+*.dylib
 cabal.project.local*