diff --git a/build/yaml-to-json.mjs b/build/yaml-to-json.mjs
new file mode 100644
index 0000000..95dab6c
--- /dev/null
+++ b/build/yaml-to-json.mjs
@@ -0,0 +1,33 @@
+import { execSync } from 'child_process';
+import { existsSync, statSync } from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+
+function isGrammarOutdate(fileName) {
+    const thisFile = fileURLToPath(import.meta.url);
+    const json = path.join(path.dirname(thisFile), '..', 'syntaxes', fileName);
+    if (!existsSync(json)) {
+        return true;
+    }
+    const yaml = json.replace('.json', '.yml');
+    const jsonState = statSync(json);
+    const yamlState = statSync(yaml);
+    if (yamlState.mtime.toString() > jsonState.mtime.toString()) {
+        console.log(`${yaml} changed, Grammar is outdate, re-generate it.`);
+        return true;
+    }
+    return false;
+}
+
+function yamlToJson() {
+    if (isGrammarOutdate('cmake.tmLanguage.json')) {
+        execSync('npm run grammar-cmake');
+    }
+
+    if (isGrammarOutdate('cmakecache.tmLanguage.json')) {
+        execSync('npm run grammar-cmakecache');
+    }
+}
+
+yamlToJson();
diff --git a/package.json b/package.json
index c95f93b..9d54efc 100644
--- a/package.json
+++ b/package.json
@@ -97,7 +97,7 @@
     "vscode:prepublish": "npm run compile",
     "grammar-cmake": "npx js-yaml ./syntaxes/cmake.tmLanguage.yml > ./syntaxes/cmake.tmLanguage.json",
     "grammar-cmakecache": "npx js-yaml ./syntaxes/cmakecache.tmLanguage.yml > ./syntaxes/cmakecache.tmLanguage.json",
-    "grammar": "npm run grammar-cmake && npm run grammar-cmakecache",
+    "grammar": "node ./build/yaml-to-json.mjs",
     "compile": "npm run grammar && tsc -p ./",
     "watch": "npm run grammar && tsc -watch -p ./",
     "pretest": "npm run compile && npm run lint",