diff --git a/.forgejo/workflows/build.yml b/.forgejo/workflows/build.yml
index 40dc8b668..ea4dfbd96 100644
--- a/.forgejo/workflows/build.yml
+++ b/.forgejo/workflows/build.yml
@@ -30,6 +30,12 @@ on:
 jobs:
   build-and-publish:
     runs-on: lucy-rust
+    # Run every step with bash, not the runner's default dash — the steps use
+    # `set -euo pipefail` (pipefail is a bashism; dash errors "Illegal option").
+    # The straw-build image ships /usr/bin/bash.
+    defaults:
+      run:
+        shell: bash
     container:
       image: git.sulkta.com/sulkta-infra/straw-build:latest
     steps: