diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 65c1c92f36..de744ca3f0 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -2625,7 +2625,7 @@ namespace ts {
     /**
      * Gets a custom text range to use when emitting source maps.
      */
-    export function getSourceMapRange(node: Node) {
+    export function getSourceMapRange(node: Node): SourceMapRange {
         const emitNode = node.emitNode;
         return (emitNode && emitNode.sourceMapRange) || node;
     }