diff --git a/public/steam/steamclientpublic.h b/public/steam/steamclientpublic.h
index a0facb30..778af278 100644
--- a/public/steam/steamclientpublic.h
+++ b/public/steam/steamclientpublic.h
@@ -637,6 +637,13 @@ inline bool CSteamID::IsValid() const
 	return true;
 }
 
+const unsigned int k_unSteamAccountIDMask = 0xFFFFFFFF;
+const unsigned int k_unSteamAccountInstanceMask = 0x000FFFFF;
+// we allow 3 simultaneous user account instances right now, 1= desktop, 2 = console, 4 = web, 0 = all
+const unsigned int k_unSteamUserDesktopInstance	= 1;	 
+const unsigned int k_unSteamUserConsoleInstance	= 2;
+const unsigned int k_unSteamUserWebInstance		= 4;
+
 
 // generic invalid CSteamID
 const CSteamID k_steamIDNil;