diff --git a/.gitea/workflows/reusable-engine-launcher.yml b/.gitea/workflows/reusable-engine-launcher.yml
index a06d507..7659f65 100644
--- a/.gitea/workflows/reusable-engine-launcher.yml
+++ b/.gitea/workflows/reusable-engine-launcher.yml
@@ -40,6 +40,8 @@ jobs:
             libx11-dev libxrandr-dev libxi-dev libxcursor-dev libxinerama-dev \
             libxkbcommon-dev libwayland-dev \
             libgl1-mesa-dev libglu1-mesa-dev
+          # xvfb: headless X server for window-opening smoke tests
+          apt-get install -y xvfb
 
       - name: Configure CMake
         run: cmake -B build -DCMAKE_BUILD_TYPE=${{ inputs.build_type }}