diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index aa06371..38831c5 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -28,7 +28,7 @@ jobs:
         name: Build CUDA base image
         run: |
           docker build \
-            --build-arg BASE=python:${{ matrix.distribution }}
+            --build-arg BASE=python:${{ matrix.distribution }} \
             -t cuda:${{ matrix.distribution }} \
             -f docker/cuda-10-0.dockerfile .
           echo "::set-env name=base::cuda:${{ matrix.distribution }}"