diff --git a/.github/workflows/observability-charm-tests.yaml b/.github/workflows/observability-charm-tests.yaml
index 233ad4b66..fee64539d 100644
--- a/.github/workflows/observability-charm-tests.yaml
+++ b/.github/workflows/observability-charm-tests.yaml
@@ -38,7 +38,7 @@ jobs:
         run: pip install tox~=4.2
 
       - name: Run the charm's unit tests
-        if: !(matrix.disabled)
+        if: ${{ !(matrix.disabled) }}
         run: tox -vve unit
 
       - name: Run the charm's static analysis checks