diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 07bccf4a5ef..4e401c5c9b3 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -110,6 +110,7 @@ namespace ts {
         {
             name: "out",
             type: "string",
+            isFilePath: true,
             description: Diagnostics.Concatenate_and_emit_output_to_single_file,
             paramType: Diagnostics.FILE,
         },