diff --git a/packages/babel-code-frame/src/index.js b/packages/babel-code-frame/src/index.js
index 4d260b65eb..f5581344e2 100644
--- a/packages/babel-code-frame/src/index.js
+++ b/packages/babel-code-frame/src/index.js
@@ -84,7 +84,7 @@ function highlight(text: string) {
 export default function (
   rawLines: string,
   lineNumber: number,
-  colNumber: number,
+  colNumber: ?number,
   opts: Object = {},
 ): string {
   colNumber = Math.max(colNumber, 0);