diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index 67f7ee2aaad..b133f9e986e 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -190,7 +190,7 @@ namespace ts {
                 configFileName = combinePaths(fileOrDirectory, "tsconfig.json");
             }
             else {
-                if (!/^tsconfig(?:-.*)?.json$/.test(getBaseFileName(fileOrDirectory))) {
+                if (!/^tsconfig(?:-.*)?\.json$/.test(getBaseFileName(fileOrDirectory))) {
                     reportDiagnostic(createCompilerDiagnostic(Diagnostics.The_project_file_name_is_not_in_tsconfig_Asterisk_json_format_Colon_0, commandLine.options.project));
                     return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
                 }