diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 030b66813a5..48d90bbca51 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2675,7 +2675,7 @@ namespace ts {
             if (sourceFiles.length) {
                 const jsFilePath = options.outFile || options.out;
                 const sourceMapFilePath = getSourceMapFilePath(jsFilePath, options);
-                const declarationFilePath = options.declaration ? removeFileExtension(jsFilePath) + ".d.ts" : undefined;
+                const declarationFilePath = options.declaration ? removeFileExtension(jsFilePath) + ".d.ts" : "";
                 action({ jsFilePath, sourceMapFilePath, declarationFilePath }, createBundle(sourceFiles), emitOnlyDtsFiles);
             }
         }