diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index d017e64e333..f8905e34126 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -37,7 +37,7 @@ namespace ts {
 
         showTSConfigCorrectly("Default initialized TSConfig", ["--showConfig"]);
 
-        showTSConfigCorrectly("Show TSConfig with files options", ["--showConfig", "file0.st", "file1.ts", "file2.ts"]);
+        showTSConfigCorrectly("Show TSConfig with files options", ["--showConfig", "file0.ts", "file1.ts", "file2.ts"]);
 
         showTSConfigCorrectly("Show TSConfig with boolean value compiler options", ["--showConfig", "--noUnusedLocals"]);
 
diff --git a/tests/baselines/reference/showConfig/Show TSConfig with files options/tsconfig.json b/tests/baselines/reference/showConfig/Show TSConfig with files options/tsconfig.json
index 2b2c1385bab..74272400966 100644
--- a/tests/baselines/reference/showConfig/Show TSConfig with files options/tsconfig.json	
+++ b/tests/baselines/reference/showConfig/Show TSConfig with files options/tsconfig.json	
@@ -1,7 +1,7 @@
 {
     "compilerOptions": {},
     "files": [
-        "./file0.st",
+        "./file0.ts",
         "./file1.ts",
         "./file2.ts"
     ]