diff --git a/.github/workflows/flowzone.yml b/.github/workflows/flowzone.yml
index c480b34..2945e48 100644
--- a/.github/workflows/flowzone.yml
+++ b/.github/workflows/flowzone.yml
@@ -23,8 +23,10 @@ jobs:
     with:
       docker_images: ""
       # open-balena-base/GLIBC compatibility
-      custom_runs_on: |
-        [["ubuntu-20.04"]]
+      custom_test_matrix: >
+        {
+          "os": [["ubuntu-20.04"]]
+        }
       docker_runs_on: |
         {
           "linux/amd64": ["ubuntu-20.04"]