diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0c941246..50db2794 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -8,7 +8,11 @@ env:
   DB_PORT: 5432
 
 name: CI
-on: [push, pull_request]
+on:
+  push:
+    branches-ignore: "master"
+  pull_request:
+    branches: "*"
 
 jobs:
   test:
diff --git a/Dockerfile b/Dockerfile
index ad0a5e2e..5f5b9280 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,7 +10,7 @@ ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
 RUN mkdir -p $RAILS_ROOT
 WORKDIR $RAILS_ROOT
 
-ARG BUILD_PACKAGES="build-base curl-dev git"
+ARG BUILD_PACKAGES="build-base curl-dev git shared-mime-info"
 ARG DEV_PACKAGES="postgresql-dev sqlite-libs sqlite-dev yaml-dev zlib-dev nodejs yarn"
 ARG RUBY_PACKAGES="tzdata"