diff --git a/.github/workflows/bigendian.yml b/.github/workflows/bigendian.yml
index db4433e..27fb10b 100644
--- a/.github/workflows/bigendian.yml
+++ b/.github/workflows/bigendian.yml
@@ -20,7 +20,9 @@ jobs:
     - name: Install
       run: |
         sudo apt-get update
-        sudo apt install -y qemu-system-ppc64 qemu-user
+        # User-mode QEMU runs the ppc64 test binary. qemu-system-ppc64 is only a
+        # virtual package on Ubuntu 26.04, so apt cannot install it by that name.
+        sudo apt install -y qemu-user qemu-user-binfmt
     - name: Test
       run: |
-        GOARCH=ppc64 go test ./...
\ No newline at end of file
+        GOARCH=ppc64 go test ./...
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5feb159..056a930 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,7 +5,8 @@ jobs:
     strategy:
       matrix:
         go-version: [1.22.x]
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        # macos-latest is macOS 26, whose dyld rejects Go 1.22 binaries (no LC_UUID).
+        os: [ubuntu-latest, macos-15, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Install Go