diff --git a/External/kanata b/External/kanata
index 6a05a4a3f..12b64a6fb 160000
--- a/External/kanata
+++ b/External/kanata
@@ -1 +1 @@
-Subproject commit 6a05a4a3fea117eb1d240d9c77492fb9ed02f7d1
+Subproject commit 12b64a6fb7354593558918e3b4d4f5289fea8754
diff --git a/Scripts/build-kanata.sh b/Scripts/build-kanata.sh
index c7bb009cf..12dbe0d7c 100755
--- a/Scripts/build-kanata.sh
+++ b/Scripts/build-kanata.sh
@@ -51,9 +51,13 @@ echo "📁 Build directory: $BUILD_DIR"
 
 # TCC-Safe Caching Logic
 function calculate_source_hash() {
-    # Generate hash based on kanata source files (excluding build artifacts)
+    # Generate hash based on kanata source files (excluding build artifacts).
+    # Includes C/C++ sources: the fork vendors the karabiner-driverkit crate
+    # (driverkit/c_src), and a .cpp/.hpp-only change must invalidate the cache
+    # or a stale engine silently ships (bit MAL-57 Layer 3).
     cd "$KANATA_SOURCE"
-    find . \( -name "*.rs" -o -name "*.toml" -o -name "*.lock" \) \
+    find . \( -name "*.rs" -o -name "*.toml" -o -name "*.lock" \
+              -o -name "*.c" -o -name "*.cpp" -o -name "*.h" -o -name "*.hpp" \) \
         -not -path "./target/*" \
         -exec shasum -a 256 {} + 2>/dev/null | shasum -a 256 | cut -d' ' -f1
 }