diff --git a/rtl/freebsd/unxsockh.inc b/rtl/freebsd/unxsockh.inc
index 1e182bd85d..25aed50eda 100644
--- a/rtl/freebsd/unxsockh.inc
+++ b/rtl/freebsd/unxsockh.inc
@@ -346,4 +346,6 @@ Const
   MSG_COMPAT    = $8000;
   MSG_SOCALLBCK = $10000;
   MSG_NOSIGNAL  = $20000;              { Do not generate SIGPIPE }
-
+  
+  INVALID_SOCKET = -1;
+  SOCKET_ERROR = -1;
diff --git a/rtl/netware/netwsockh.inc b/rtl/netware/netwsockh.inc
index 55a2c45e50..7a43a3f7ce 100644
--- a/rtl/netware/netwsockh.inc
+++ b/rtl/netware/netwsockh.inc
@@ -52,3 +52,7 @@ const
        PF_ATM = AF_ATM;
        PF_INET6 = AF_INET6;
        PF_MAX = AF_MAX;
+       
+  INVALID_SOCKET = -1;
+  SOCKET_ERROR = -1;
+
diff --git a/rtl/netwlibc/netwsockh.inc b/rtl/netwlibc/netwsockh.inc
index 55a2c45e50..f8cdae57cc 100644
--- a/rtl/netwlibc/netwsockh.inc
+++ b/rtl/netwlibc/netwsockh.inc
@@ -52,3 +52,6 @@ const
        PF_ATM = AF_ATM;
        PF_INET6 = AF_INET6;
        PF_MAX = AF_MAX;
+       
+  INVALID_SOCKET = -1;
+  SOCKET_ERROR = -1;
diff --git a/rtl/os2/sockets.pas b/rtl/os2/sockets.pas
index 9aa1f4fe4a..216b642558 100644
--- a/rtl/os2/sockets.pas
+++ b/rtl/os2/sockets.pas
@@ -124,6 +124,9 @@ Type
 // OS/2 stack based on BSD stack
 {$DEFINE BSD}
 {$I socketsh.inc}
+  INVALID_SOCKET = TSocket(not(0));
+  SOCKET_ERROR = -1;
+
 
 Implementation