diff --git a/lib/System/Win32/Mutex.inc b/lib/System/Win32/Mutex.inc
index 85cf0a7f9b5..7c1723be73f 100644
--- a/lib/System/Win32/Mutex.inc
+++ b/lib/System/Win32/Mutex.inc
@@ -22,7 +22,7 @@
 namespace llvm {
 using namespace sys;
 
-Mutex::Mutex()
+Mutex::Mutex(bool /*recursive*/)
 {
   data_ = new CRITICAL_SECTION;
   InitializeCriticalSection((LPCRITICAL_SECTION)data_);