diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index d26f0d52020..f7d473b738a 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-18.04
     strategy:
       matrix:
-        python: [2.7, 3.6, 3.7, 3.8, 3.9, 3.10]
+        python: [2.7, 3.6, 3.7, 3.8, 3.9, '3.10']
         modules_tool: [Lmod-6.6.3, Lmod-7.8.22, Lmod-8.1.14]
         module_syntax: [Lua, Tcl]
         # exclude some configurations: only test Tcl module syntax with Lmod 7.x and Python 2.7 & 3.6
@@ -20,7 +20,7 @@ jobs:
             module_syntax: Tcl
           - python: 3.9
             module_syntax: Tcl
-          - python: 3.10
+          - python: '3.10'
             module_syntax: Tcl
       fail-fast: false
     steps: