diff --git a/tools/config_gen.py b/tools/config_gen.py
index 76e09e750..b72130d9e 100644
--- a/tools/config_gen.py
+++ b/tools/config_gen.py
@@ -21,12 +21,19 @@ def main():
         default=sys.stdin,
         help="Input YAML file.",
     )
+    parser.add_argument(
+        "--skip-unchanged",
+        dest="skip_unchanged",
+        action="store_true",
+        help="Only write output file if new content is different"
+    )
     parser.add_argument(
         "--write-c",
         metavar="OUT_FILE",
         dest="out_file_c",
         nargs="?",
-        type=argparse.FileType("w"),
+        # Use a+ mode to open in read/write mode without truncating existing contents
+        type=argparse.FileType("a+"),
         const=sys.stdout,
         default=None,
         help="Output C header file.",
@@ -36,25 +43,25 @@ def main():
         metavar="OUT_FILE",
         dest="out_file_json",
         nargs="?",
-        type=argparse.FileType("w"),
+        type=argparse.FileType("a+"),
         const=sys.stdout,
         default=None,
         help="Output JSON file.",
     )
     args = parser.parse_args()
     generate(args.in_file_yaml, out_file_c=args.out_file_c,
-             out_file_json=args.out_file_json)
+             out_file_json=args.out_file_json, skip_unchanged=args.skip_unchanged)
 
 
-def generate(in_file_yaml, out_file_c=None, out_file_json=None):
+def generate(in_file_yaml, out_file_c=None, out_file_json=None, skip_unchanged=False):
     config = yaml.safe_load(in_file_yaml)
     if out_file_c is not None:
-        generate_c(config, out_file_c)
+        generate_c(config, out_file_c, skip_unchanged)
     if out_file_json is not None:
-        generate_json(config, out_file_json)
+        generate_json(config, out_file_json, skip_unchanged)
 
 
-def generate_c(config, out_file):
+def generate_c(config, out_file, skip_unchanged):
     header_contents = "#pragma once\n\n"
 
     for key, value in config.items():
@@ -76,11 +83,24 @@ def generate_c(config, out_file):
 
         header_contents += f"{entry}\n"
 
-    out_file.write(header_contents)
+    write_file_lazy(out_file, header_contents, skip_unchanged)
 
 
-def generate_json(config, out_file):
-    json.dump(config, out_file, indent=4)
+def generate_json(config, out_file, skip_unchanged):
+    json_contents = json.dumps(config, indent=4)
+    write_file_lazy(out_file, json_contents, skip_unchanged)
+
+
+def write_file_lazy(out_file, content, skip_unchanged):
+    if out_file == sys.stdout:
+        out_file.write(content)
+        return
+
+    out_file.seek(0)
+    if not skip_unchanged or out_file.read() != content:
+        out_file.seek(0)
+        out_file.truncate()
+        out_file.write(content)
 
 
 if __name__ == "__main__":