diff --git a/.github/workflows/on-demand-deployment.yaml b/.github/workflows/on-demand-deployment.yaml
index 08f141e2..66cd4621 100644
--- a/.github/workflows/on-demand-deployment.yaml
+++ b/.github/workflows/on-demand-deployment.yaml
@@ -110,6 +110,10 @@ jobs:
           cd $GITHUB_WORKSPACE
           cd scripts
           # ${{ steps.get_tag.outputs.tag }}
+
+          # Manually install PyInstaller rather than use the dev install requires from setup.py.
+          $pip_exe install pyinstaller
+
           if [ "${{ matrix.variant }}" == "mapclient" ]; then
             $python_exe prepare_mapclient_release.py ${{ matrix.tag }}
           elif [ "${{ matrix.variant }}" == "mapping-tools" ]; then