diff --git a/.github/workflows/bootstrap.yml b/.github/workflows/bootstrap.yml
index 1b1a1922c9b..0445ac75a89 100644
--- a/.github/workflows/bootstrap.yml
+++ b/.github/workflows/bootstrap.yml
@@ -17,11 +17,15 @@ on:
 jobs:
   bootstrap:
     strategy:
+      # A failure on one OS should not cancel, and so hide, the results on the others.
+      fail-fast: false
       matrix:
         os: [ubuntu-latest]
         ghc: ["9.6.7", "9.8.4", "9.10.3", "9.12.4"]
         include:
-          - os: macos-latest
+          # macos-15 rather than macos-latest until actions/runner-images#14940
+          # is fixed; see #12465.
+          - os: macos-15
             ghc: "9.12.4"
     name: Bootstrap ${{ matrix.os }} ghc-${{ matrix.ghc }}
     runs-on: ${{ matrix.os }}
diff --git a/.github/workflows/reusable-release.yml b/.github/workflows/reusable-release.yml
index 3bf83764c30..f4c0a9b4d61 100644
--- a/.github/workflows/reusable-release.yml
+++ b/.github/workflows/reusable-release.yml
@@ -231,7 +231,9 @@ jobs:
 
   build-mac-aarch64:
     name: Build binary (Mac aarch64)
-    runs-on: macos-latest
+    # macos-15 rather than macos-latest until actions/runner-images#14940
+    # is fixed; see #12465.
+    runs-on: macos-15
     env:
       MACOSX_DEPLOYMENT_TARGET: 10.13
       ADD_CABAL_ARGS: ""
@@ -534,7 +536,9 @@ jobs:
 
   test-mac-aarch64:
     name: Test binary (Mac aarch64)
-    runs-on: macos-latest
+    # macos-15 rather than macos-latest until actions/runner-images#14940
+    # is fixed; see #12465.
+    runs-on: macos-15
     needs: ["build-mac-aarch64"]
     if: ${{ inputs.test }}
     env:
diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index baf5210f87f..63099027df2 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -54,7 +54,9 @@ jobs:
         sys:
           - { os: windows-latest, shell: "C:/msys64/usr/bin/bash.exe -e {0}" }
           - { os: ubuntu-latest, shell: bash }
-          - { os: macos-latest, shell: bash }
+          # macos-15 rather than macos-latest until actions/runner-images#14940
+          # is fixed; see #12465.
+          - { os: macos-15, shell: bash }
         ghc:
           [
             # IMPORTANT: If you remove a version from this list, then add it to the old-ghcs job below.
@@ -393,7 +395,9 @@ jobs:
         sys:
           - { os: windows-latest, shell: "C:/msys64/usr/bin/bash.exe -e {0}" }
           - { os: ubuntu-latest, shell: bash }
-          - { os: macos-latest, shell: bash }
+          # macos-15 rather than macos-latest until actions/runner-images#14940
+          # is fixed; see #12465.
+          - { os: macos-15, shell: bash }
         # We only use one ghc version the used one for the next release (defined at top of the workflow)
         # We need to build an array dynamically to inject the appropriate env var in a previous job,
         # see https://docs.github.com/en/actions/learn-github-actions/expressions#fromjson