diff --git a/.forgejo/workflows/ids-lint.yml b/.forgejo/workflows/ids-lint.yml
index df6b3bc..0bb1d7f 100644
--- a/.forgejo/workflows/ids-lint.yml
+++ b/.forgejo/workflows/ids-lint.yml
@@ -29,6 +29,12 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Run IDS validations
+        # shell: bash is REQUIRED, not decoration. The runner executes `run:`
+        # blocks with /bin/sh (dash) unless told otherwise, so the GitHub
+        # original's `shopt -s globstar` dies with "shopt: not found" and
+        # exit 127 before the first file is checked. `[[ ]]` and arrays need
+        # bash too.
+        shell: bash
         # Deliberately greps output instead of trusting the exit status:
         # ifctester's CLI has no sys.exit anywhere, so a model that violates
         # every rule still exits 0. A naive `run: ifctester ...` would be a
diff --git a/.forgejo/workflows/ifc-lint.yml b/.forgejo/workflows/ifc-lint.yml
index d991afc..21d3280 100644
--- a/.forgejo/workflows/ifc-lint.yml
+++ b/.forgejo/workflows/ifc-lint.yml
@@ -26,6 +26,12 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Run IFC lint checks
+        # shell: bash is REQUIRED, not decoration. The runner executes `run:`
+        # blocks with /bin/sh (dash) unless told otherwise, so the GitHub
+        # original's `shopt -s globstar` dies with "shopt: not found" and
+        # exit 127 before the first file is checked. `[[ ]]` and arrays need
+        # bash too.
+        shell: bash
         # Gates on its own exit status: ifcopenshell.validate calls sys.exit()
         # on failure, so `set -e` fails the job.
         run: |