diff --git a/src/system_error.cpp b/src/system_error.cpp
index b40409f8..00920ffd 100644
--- a/src/system_error.cpp
+++ b/src/system_error.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define	_LIBCPP_BUILDING_SYSTEM_ERROR
+#define _LIBCPP_BUILDING_SYSTEM_ERROR
 #include "system_error"
 #include "string"
 #include "cstring"