diff --git a/scripts/modeline.py b/scripts/modeline.py
new file mode 100644
index 0000000..af2f38d
--- /dev/null
+++ b/scripts/modeline.py
@@ -0,0 +1,16 @@
+import sys
+
+modline = "// -*- Mode: c++; c-basic-offset: 4; tab-width: 4; -*-\n\n"
+
+for path in sys.argv[1:]:
+    lines = [modline]
+    with file(path) as f:
+        lines += f.readlines()
+
+    has_modeline = any([l for l in lines[1:] if l.find('Mode: c++') != -1])
+    if has_modeline:
+        continue
+
+    with file(path, 'w') as f:
+        for line in lines:
+            f.write(line)