diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 2d7c9266f2b..ab78f74f29d 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -4328,7 +4328,7 @@ module ts {
             }
             var diagnostic: DiagnosticMessage;
             if (hasExtension(filename)) {
-                if (!fileExtensionIs(filename, ".ts")) {
+                if (!options.allowNonTsExtensions && !fileExtensionIs(filename, ".ts")) {
                     diagnostic = Diagnostics.File_0_must_have_extension_ts_or_d_ts;
                 }
                 else if (!findSourceFile(filename, isDefaultLib, refFile, refPos, refEnd)) {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index c8f1c6d8b6a..5836f25891b 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -1152,6 +1152,7 @@ module ts {
         version?: boolean;
         watch?: boolean;
         preserveConstEnums?: boolean;
+        allowNonTsExtensions?: boolean;
         [option: string]: string | number | boolean;
     }