diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 9c8b05f115..d73ed33db2 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -465,6 +465,11 @@ jobs:
       # AppImage tools (linuxdeploy, appimagetool) are themselves AppImages.
       # Containers lack FUSE, so we must use the extract-and-run fallback.
       APPIMAGE_EXTRACT_AND_RUN: "1"
+    # This job runs in a container where the default run shell is dash;
+    # the AppImage steps below use bash-only syntax ([[ ]], mapfile, arrays).
+    defaults:
+      run:
+        shell: bash
     outputs:
       archive_name: ${{ steps.linux-artifacts.outputs.archive_name }}
       sig: ${{ steps.read-sig.outputs.sig }}