diff --git a/build/gulpfile.editor.js b/build/gulpfile.editor.js
index 230082e4ad9..0a7c24b4539 100644
--- a/build/gulpfile.editor.js
+++ b/build/gulpfile.editor.js
@@ -231,7 +231,10 @@ function toExternalDTS(contents) {
 
 		if (line.indexOf('declare let MonacoEnvironment') === 0) {
 			lines[i] = `declare global {\n    let MonacoEnvironment: Environment | undefined;\n}`;
-			// lines[i] = line.replace('declare namespace monaco.', 'export namespace ');
+		}
+
+		if (line.indexOf('\tMonacoEnvironment?') === 0) {
+			lines[i] = `    MonacoEnvironment?: Environment | undefined;`;
 		}
 	}
 	return lines.join('\n').replace(/\n\n\n+/g, '\n\n');