diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 9e96651f8bd..654f240b4b5 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -732,7 +732,7 @@ module Harness {
 
                 var filemap: { [name: string]: ts.SourceFile; } = {};
                 var register = (file: { unitName: string; content: string; }) => {
-                    if (file.content) {
+                    if (file.content !== undefined) {
                         var filename = Path.switchToForwardSlashes(file.unitName);
                         filemap[getCanonicalFileName(filename)] = ts.createSourceFile(filename, file.content, options.target, /*version:*/ "0");
                     }