diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 11bfe93e..c0852cdd 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -13,10 +13,9 @@ jobs:
           - {os: windows-latest, python_Version: '3.7', toxenv: 'py37'}
           - {os: windows-latest, python_Version: '3.8', toxenv: 'py38'}
           - {os: windows-latest, python_Version: '3.9', toxenv: 'py39'}
-          # Linux still not working
-          # {os: linux-latest, python_Version: '3.7', toxenv: 'py37'}
-          # {os: linux-latest, python_Version: '3.8', toxenv: 'py38'}
-          # {os: linux-latest, python_Version: '3.9', toxenv: 'py39'}
+          - {os: ubuntu-latest, python_Version: '3.7', toxenv: 'py37'}
+          - {os: ubuntu-latest, python_Version: '3.8', toxenv: 'py38'}
+          - {os: ubuntu-latest, python_Version: '3.9', toxenv: 'py39'}
           - {os: macos-latest, python_Version: '3.7', toxenv: 'py37'}
           - {os: macos-latest, python_Version: '3.8', toxenv: 'py38'}
           # missing numcodecs wheels on 3.9. conda not yet an option. see gh-51