diff --git a/utils/generate_types/index.js b/utils/generate_types/index.js
index d99a219b08..3ac4f881a5 100644
--- a/utils/generate_types/index.js
+++ b/utils/generate_types/index.js
@@ -91,7 +91,7 @@ let hadChanges = false;
     return classBody(docClassForName(className));
   });
   const classes = documentation.classesArray.filter(cls => !handledClasses.has(cls.name));
-  let output = `// This file is generated by ${__filename.substring(path.join(__dirname, '..', '..').length)}
+  let output = `// This file is generated by ${__filename.substring(path.join(__dirname, '..', '..').length).split(path.sep).join(path.posix.sep)}
 ${overrides}
 
 ${classes.map(classDesc => classToString(classDesc)).join('\n')}