diff --git a/pjlib/include/pj/compat/os_darwinos.h b/pjlib/include/pj/compat/os_darwinos.h
index e797c43..ce42333 100644
--- a/pjlib/include/pj/compat/os_darwinos.h
+++ b/pjlib/include/pj/compat/os_darwinos.h
@@ -135,6 +135,9 @@
  */
 #define PJ_THREAD_ALLOCATE_STACK    	0
 
+/* Oh well.. MacOS 10.2 doesn't have socklen_t, but 10.4 has! */
+#define PJ_HAS_SOCKLEN_T		0
+
 
 #endif	/* __PJ_COMPAT_OS_DARWINOS_H__ */
 
diff --git a/pjlib/include/pj/compat/os_linux.h b/pjlib/include/pj/compat/os_linux.h
index f0bef35..cd5acaf 100644
--- a/pjlib/include/pj/compat/os_linux.h
+++ b/pjlib/include/pj/compat/os_linux.h
@@ -119,6 +119,8 @@
  */
 #define PJ_THREAD_ALLOCATE_STACK    	0
 
+/* Linux has socklen_t */
+#define PJ_HAS_SOCKLEN_T		1
 
 
 #endif	/* __PJ_COMPAT_OS_LINUX_H__ */
diff --git a/pjlib/include/pj/compat/os_rtems.h b/pjlib/include/pj/compat/os_rtems.h
index f764f9b..3f60656 100644
--- a/pjlib/include/pj/compat/os_rtems.h
+++ b/pjlib/include/pj/compat/os_rtems.h
@@ -128,6 +128,9 @@
  */
 #define PJ_THREAD_ALLOCATE_STACK    1
 
+/* RTEMS has socklen_t (does it? )*/
+#define PJ_HAS_SOCKLEN_T	    1
+
 
 
 
diff --git a/pjlib/include/pj/compat/os_sunos.h b/pjlib/include/pj/compat/os_sunos.h
index 56c4830..d3c9650 100644
--- a/pjlib/include/pj/compat/os_sunos.h
+++ b/pjlib/include/pj/compat/os_sunos.h
@@ -122,6 +122,9 @@
  */
 #define PJ_THREAD_ALLOCATE_STACK    	0
 
+/* SunOS has socklen_t (does it? )*/
+#define PJ_HAS_SOCKLEN_T	    1
+
 
 
 #endif	/* __PJ_COMPAT_OS_SUNOS_H__ */