diff --git a/src/api/configuration.ts b/src/api/configuration.ts
index b820976a..4a89efae 100644
--- a/src/api/configuration.ts
+++ b/src/api/configuration.ts
@@ -26,7 +26,7 @@ export interface BundlerOptions {
     ignore?: string[];
     noParse?: string[];
     resolve?: Resolve;
-    sourceMap: boolean;
+    sourceMap?: boolean;
     transforms?: Transform[];
     validateSyntax?: boolean;
 }