diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 4784ab5ff..6f17ccdfb 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -89,7 +89,7 @@ jobs:
         if: ${{ github.event_name == 'pull_request' || github.repository != 'mapnik/mapnik' }}
         shell: "bash"
         run: >
-          `./vcpkg/vcpkg fetch nuget | tail -n 1`
+          ${{ env.mono }} `./vcpkg/vcpkg fetch nuget | tail -n 1`
           sources add
           -source "${{ inputs.NUGET_REGISTRY }}"
           -storepasswordincleartext
@@ -101,7 +101,7 @@ jobs:
         if: ${{ github.event_name == 'pull_request' || github.repository != 'mapnik/mapnik' }}
         shell: "bash"
         run: >
-          `./vcpkg/vcpkg fetch nuget | tail -n 1`
+          ${{ env.mono }} `./vcpkg/vcpkg fetch nuget | tail -n 1`
           setapikey "${{ secrets.GITHUB_TOKEN }}" -Source "${{ inputs.NUGET_REGISTRY }}"
 
       - name: Configure CMake