diff --git a/.github/actions/2-build-bootstrap/action.yml b/.github/actions/2-build-bootstrap/action.yml
index a7becdcaeb8..414fa4fbe82 100644
--- a/.github/actions/2-build-bootstrap/action.yml
+++ b/.github/actions/2-build-bootstrap/action.yml
@@ -5,12 +5,15 @@ inputs:
     default: ''
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: Check CMake and ninja versions
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cmake --version
@@ -25,6 +28,7 @@ runs:
           -DBUILD_SHARED_LIBS=OFF
           ${{ inputs.cmake_flags }}
         arch: ${{ inputs.arch }}
+        shell: ${{ inputs.shell }}
 
     - run: ../bootstrap-ldc/bin/ldc2 --version
-      shell: bash
+      shell: ${{ inputs.shell }}
diff --git a/.github/actions/2a-build-pgo/action.yml b/.github/actions/2a-build-pgo/action.yml
index 0933ebc6264..d3831539a4f 100644
--- a/.github/actions/2a-build-pgo/action.yml
+++ b/.github/actions/2a-build-pgo/action.yml
@@ -5,6 +5,9 @@ inputs:
     default: ''
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
@@ -20,11 +23,12 @@ runs:
           "-DDFLAGS_LDC=-fprofile-generate -vp-counters-per-site=1.5"
           ${{ inputs.cmake_flags }}
         arch: ${{ inputs.arch }}
+        shell: ${{ inputs.shell }}
       env:
         LLVM_PROFILE_FILE: ${{ github.workspace }}/../pgo-ldc/%p.profraw
 
     - name: Merge PGO profiles # to ../pgo-ldc/merged.profdata
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ../pgo-ldc
diff --git a/.github/actions/3-build-native/action.yml b/.github/actions/3-build-native/action.yml
index 3683f67fd8c..c87f2a77058 100644
--- a/.github/actions/3-build-native/action.yml
+++ b/.github/actions/3-build-native/action.yml
@@ -8,6 +8,9 @@ inputs:
   with_pgo:
     required: false
     default: false
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
@@ -15,6 +18,8 @@ runs:
     - name: 'Posix: Build mimalloc'
       if: runner.os != 'Windows'
       uses: ./.github/actions/helper-mimalloc
+      with:
+        shell: ${{ inputs.shell }}
 
     - name: Build LDC & LDC D unittests & defaultlib unittest runners
       uses: ./.github/actions/helper-build-ldc
@@ -28,6 +33,7 @@ runs:
           ${{ inputs.with_pgo == 'true' && '-DDFLAGS_LDC=-fprofile-use=../pgo-ldc/merged.profdata' || '' }}
         build_targets: all ldc2-unittest all-test-runners
         arch: ${{ inputs.arch }}
+        shell: ${{ inputs.shell }}
 
     - run: ../build/bin/ldc2 --version
-      shell: bash
+      shell: ${{ inputs.shell }}
diff --git a/.github/actions/4a-test-ldc2/action.yml b/.github/actions/4a-test-ldc2/action.yml
index da2f7e51d01..ba5702974dc 100644
--- a/.github/actions/4a-test-ldc2/action.yml
+++ b/.github/actions/4a-test-ldc2/action.yml
@@ -1,6 +1,10 @@
 name: Run LDC D unittests
+inputs:
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
     - run: cd ../build && ctest --output-on-failure -R "ldc2-unittest"
-      shell: bash
+      shell: ${{ inputs.shell }}
diff --git a/.github/actions/4b-test-lit/action.yml b/.github/actions/4b-test-lit/action.yml
index 3bdcfd3b239..6e860716810 100644
--- a/.github/actions/4b-test-lit/action.yml
+++ b/.github/actions/4b-test-lit/action.yml
@@ -2,13 +2,16 @@ name: Run LIT testsuite
 inputs:
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: 'Posix: Run LIT testsuite'
       if: runner.os != 'Windows'
-      shell: bash
+      shell: ${{ inputs.shell }}
       # temporarily add LLVM bin dir to PATH, so that e.g. wasm-ld is found
       run: cd ../build && PATH="$PWD/../llvm/bin:$PATH" ctest -V -R "lit-tests"
 
diff --git a/.github/actions/4c-test-dmd/action.yml b/.github/actions/4c-test-dmd/action.yml
index 22dbea1f942..897b13918e4 100644
--- a/.github/actions/4c-test-dmd/action.yml
+++ b/.github/actions/4c-test-dmd/action.yml
@@ -2,13 +2,16 @@ name: Run DMD testsuite
 inputs:
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: 'Posix: Run DMD testsuite'
       if: runner.os != 'Windows'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: cd ../build && ctest -V -R "dmd-testsuite"
 
     - name: 'Windows: Run DMD testsuite'
diff --git a/.github/actions/4d-test-libs/action.yml b/.github/actions/4d-test-libs/action.yml
index ce6021e3d0d..7a318ba2470 100644
--- a/.github/actions/4d-test-libs/action.yml
+++ b/.github/actions/4d-test-libs/action.yml
@@ -2,13 +2,16 @@ name: Run defaultlib unittests & druntime integration tests
 inputs:
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: 'Posix: Run defaultlib unittests & druntime integration tests'
       if: runner.os != 'Windows'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ../build
diff --git a/.github/actions/5-install/action.yml b/.github/actions/5-install/action.yml
index 52d177e6a91..9085d4de05c 100644
--- a/.github/actions/5-install/action.yml
+++ b/.github/actions/5-install/action.yml
@@ -5,12 +5,15 @@ inputs:
   cross_compiling:
     required: false
     default: false
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: Install LDC
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -44,7 +47,7 @@ runs:
         fi
 
     - name: Make portable
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -57,12 +60,12 @@ runs:
         cat install/etc/ldc2.conf
 
     - name: Rename the installation dir to test portability
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: mv ../install ../installed
 
     - name: 'Windows: Copy curl & MinGW-w64-based libs'
       if: runner.os == 'Windows'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
diff --git a/.github/actions/6-integration-test/action.yml b/.github/actions/6-integration-test/action.yml
index b1979c21be7..ca03d1e47e0 100644
--- a/.github/actions/6-integration-test/action.yml
+++ b/.github/actions/6-integration-test/action.yml
@@ -1,14 +1,18 @@
 name: Run a few integration tests against the installed compiler
+inputs:
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: Generate hello.d
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: echo 'void main() { import std.stdio; writefln("Hello world, %d bits", size_t.sizeof * 8); }' > ../hello.d
 
     - name: Run hello-world integration test with shared libs
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -24,7 +28,7 @@ runs:
         fi
 
     - name: Run hello-world integration test with LTO
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -40,7 +44,7 @@ runs:
     - name: Run dynamic-compile integration test
       # disabled since LLVM 12, needs https://github.com/ldc-developers/ldc/pull/3184
       if: '!always()'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -51,7 +55,7 @@ runs:
         installed/bin/ldc2 -enable-dynamic-compile -run ldc/tests/dynamiccompile/array.d
 
     - name: Run ImportC integration test
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
diff --git a/.github/actions/7-package/action.yml b/.github/actions/7-package/action.yml
index e2d1e109cb7..14bc016d753 100644
--- a/.github/actions/7-package/action.yml
+++ b/.github/actions/7-package/action.yml
@@ -8,12 +8,15 @@ inputs:
   cross_target_triple:
     required: false
     default: ''
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - name: Set DMD environment variable
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -25,7 +28,7 @@ runs:
         echo "DMD=$DMD" >> $GITHUB_ENV
 
     - name: Build & copy dub
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -41,7 +44,7 @@ runs:
         fi
 
     - name: Build & copy dlang tools
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -56,7 +59,7 @@ runs:
         cp bin/{rdmd,ddemangle,dustmite} ../installed/bin/
 
     - name: Build & copy reggae
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
@@ -84,7 +87,7 @@ runs:
         fi
 
     - name: Pack installation dir
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -euxo pipefail
         cd ..
@@ -132,7 +135,7 @@ runs:
 
     - name: 'Linux: Pack source dir'
       if: runner.os == 'Linux' && inputs.os == ''
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         git clean -dffx
@@ -146,7 +149,7 @@ runs:
         zip -r -9 artifacts/$artifactName.zip $artifactName >/dev/null
 
     - name: 'Move artifacts dir for uploading'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: mv ../artifacts ./
 
     - name: Upload artifact(s)
diff --git a/.github/actions/helper-build-ldc/action.yml b/.github/actions/helper-build-ldc/action.yml
index 3fafd106f0c..54d42d7f87b 100644
--- a/.github/actions/helper-build-ldc/action.yml
+++ b/.github/actions/helper-build-ldc/action.yml
@@ -18,12 +18,15 @@ inputs:
     default: 'all'
   arch:
     required: false # Windows only
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
 
     - if: runner.os != 'Windows'
-      shell: bash
+      shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..
diff --git a/.github/actions/helper-mimalloc/action.yml b/.github/actions/helper-mimalloc/action.yml
index ed5efb0bf2b..8a69196e0b6 100644
--- a/.github/actions/helper-mimalloc/action.yml
+++ b/.github/actions/helper-mimalloc/action.yml
@@ -3,10 +3,13 @@ inputs:
   cmake_flags:
     required: false
     default: ''
+  shell:
+    required: false
+    default: bash
 runs:
   using: composite
   steps:
-    - shell: bash
+    - shell: ${{ inputs.shell }}
       run: |
         set -eux
         cd ..