diff --git a/.github/actions/install-aiida-core/action.yml b/.github/actions/install-aiida-core/action.yml
index b35f83eab..890eff1b1 100644
--- a/.github/actions/install-aiida-core/action.yml
+++ b/.github/actions/install-aiida-core/action.yml
@@ -18,6 +18,10 @@ inputs:
     default: 'true'
     required: false
 
+defaults:
+  run:
+    shell: bash
+
 runs:
   using: composite
   steps: