diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 009033208..b4d169cbf 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -182,3 +182,67 @@ jobs:
 
       - name: Run test-fizzy
         run: zig build test-fizzy --summary all -- ${{ steps.probe.outputs.args }}
+
+  # fizzyedit/SDL's FizzyXkb suite: SDL's Wayland driver loads, and builds its keymap's modifier
+  # levels right, on the oldest supported distribution as well as a current one. This package
+  # builds SDL against libxkbcommon 1.13's headers; Ubuntu 24.04 ships libxkbcommon 1.6, which
+  # lacks `xkb_keymap_mod_get_mask` (1.10), 26.04 has 1.13. So 24.04 runs SDL's fallback that
+  # builds the modifier masks from their indices, and 26.04 the 1.10 path.
+  #
+  # Weston runs on its X11 backend inside Xvfb rather than headless: the headless backend has
+  # no seat, the X11 one has a keyboard with the X server's layout, and the suite checks German
+  # (de) levels.
+  test-fizzy-xkb:
+    strategy:
+      fail-fast: false
+      matrix:
+        distro: ["ubuntu:24.04", "ubuntu:26.04"]
+    runs-on: ubuntu-latest
+    container: ${{ matrix.distro }}
+    steps:
+      - name: Install tools, Xvfb and weston
+        run: |
+          apt-get update
+          DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+            ca-certificates git xz-utils \
+            xvfb xauth x11-xkb-utils x11-xserver-utils xkb-data weston \
+            libx11-6 libxext6 libxrandr2 libxcursor1 libxi6 libxfixes3 libxss1 libxtst6 \
+            libwayland-client0 libwayland-cursor0 libwayland-egl1 libxkbcommon0 libdecor-0-0
+          dpkg-query -W libxkbcommon0 libwayland-client0 weston
+
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Zig
+        uses: mlugg/setup-zig@v2
+        with:
+          version: 0.16.0
+
+      - name: Workaround Zig 0.16.0 ZIP unpack failure
+        # https://codeberg.org/ziglang/zig/issues/31964
+        run: mkdir -p "${ZIG_GLOBAL_CACHE_DIR}/tmp"
+
+      - name: Build test-fizzy
+        run: zig build test-fizzy --summary all -- --list
+
+      - name: Run FizzyXkb on Wayland (weston's X11 backend in Xvfb, de layout)
+        env:
+          DISPLAY: ":99"
+          WAYLAND_DISPLAY: wayland-fizzy
+          FIZZY_TEST_XKB_LAYOUT: de
+        run: |
+          export XDG_RUNTIME_DIR="$(mktemp -d)"
+          chmod 700 "$XDG_RUNTIME_DIR"
+          Xvfb "$DISPLAY" -screen 0 1280x1024x24 -nolisten tcp -noreset &
+          xvfb_pid=$!
+          for i in $(seq 50); do xset q >/dev/null 2>&1 && break; sleep 0.1; done
+          # Weston's X11 backend builds its keymap from the layout setxkbmap sets on the root
+          # window. -noreset, or Xvfb resets the layout each time its last client disconnects.
+          setxkbmap -layout de
+          setxkbmap -query
+          weston --backend=x11 --renderer=pixman --width=1024 --height=768 \
+            --socket="$WAYLAND_DISPLAY" --idle-time=0 &
+          weston_pid=$!
+          for i in $(seq 50); do [ -S "$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY" ] && break; sleep 0.1; done
+          zig build test-fizzy --summary all -- --filter FizzyXkb
+          kill "$weston_pid" "$xvfb_pid"
diff --git a/build.zig b/build.zig
index 24c1bcfbe..b919bbbf4 100644
--- a/build.zig
+++ b/build.zig
@@ -234,4 +234,5 @@ const sdl_test_sources = [_][]const u8{
 const fizzy_test_sources = [_][]const u8{
     "testfizzy.c",
     "testautomation_fizzy_gpu.c",
+    "testautomation_fizzy_xkb.c",
 };
diff --git a/build.zig.zon b/build.zig.zon
index c02703651..6bdafbf58 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -5,13 +5,14 @@
     .minimum_zig_version = "0.16.0",
     .dependencies = .{
         // fizzyedit/SDL: release-3.4.16 with fizzy's patches on top. TEST PIN: branch
-        // `test/fizzy-gpu-suite`, `fizzy-3.4` (tag `fizzy-3.4.16-5`) plus the test suite for
-        // patch 1, untagged until it is reviewed and moved onto `fizzy-3.4`. Pinned by commit.
-        // `.version` is still the SDL release it is based on: `build.zig` reads it for the
-        // library's SO version.
+        // `wayland/xkb-mod-mask-optional`, `fizzy-3.4` (tag `fizzy-3.4.16-6`) plus the suite for
+        // the Wayland driver on an older libxkbcommon and patch 8 making `xkb_keymap_mod_get_mask`
+        // optional at runtime, untagged until it is reviewed and moved onto `fizzy-3.4`. Pinned by
+        // commit. `.version` is still the SDL release it is based on: `build.zig` reads it for
+        // the library's SO version.
         .sdl = .{
-            .url = "https://github.com/fizzyedit/SDL/archive/4839ede0ed6edf3d0f94af83bc79e59b20340aef.tar.gz",
-            .hash = "N-V-__8AABSV-AKS32FsG_ErVq84xfWjO_iibVYaWCROsjJy",
+            .url = "https://github.com/fizzyedit/SDL/archive/36dda37b20cb70ce0feb79ba1340858e9cd41ac5.tar.gz",
+            .hash = "N-V-__8AANe4-AK4xmMHFWdXiPun3hihTxQJCHKC4gmCsDEQ",
             .version = "3.4.16",
         },
         .dbus = .{