diff --git a/Headers/Foundation/NSXPCConnection.h b/Headers/Foundation/NSXPCConnection.h
index 3301ac8c2..e0db9d594 100644
--- a/Headers/Foundation/NSXPCConnection.h
+++ b/Headers/Foundation/NSXPCConnection.h
@@ -34,7 +34,7 @@
 
 #if defined(_WIN32)
 #if defined(_MSC_VER)
-typedef unsigned pid_t;
+typedef int pid_t;
 #endif
 typedef unsigned gid_t;
 typedef unsigned uid_t;