diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index aa61ad94..1180974f 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -8,7 +8,7 @@ jobs:
     name: ${{ matrix.python-version }} on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     strategy:
-      max-parallel: 6
+      max-parallel: 12
       matrix:
         python-version: [2.7, 3.5, 3.6, 3.7, 3.8]
         os: [ubuntu-latest, macos-latest] # TODO: windows-latest