diff --git a/doc/man-sections/client-options.rst b/doc/man-sections/client-options.rst
index a06948e..5ca85e0 100644
--- a/doc/man-sections/client-options.rst
+++ b/doc/man-sections/client-options.rst
@@ -430,7 +430,10 @@
         The version of the operating system, e.g. 6.1 for Windows 7.
         This may be set by the client UI/GUI using ``--setenv``.
         On Windows systems it is automatically determined by openvpn
-        itself.
+        itself.  On other platforms OpenVPN will default to sending
+        the information returned by the `uname()` system call in
+        the `release` field, which is usually the currently running
+        kernel version.  This is highly system specific, though.
 
   :code:`UV_<name>=<value>`
         Client environment variables whose names start with
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 8040e7b..93e31f1 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -2010,6 +2010,10 @@
             buf_printf(&out, "IV_SSL=%s\n", get_ssl_library_version() );
 #if defined(_WIN32)
             buf_printf(&out, "IV_PLAT_VER=%s\n", win32_version_string(&gc, false));
+#else
+            struct utsname u;
+            uname(&u);
+            buf_printf(&out, "IV_PLAT_VER=%s\n", u.release);
 #endif
         }
 
diff --git a/src/openvpn/syshead.h b/src/openvpn/syshead.h
index 83a48fc..33a90c1 100644
--- a/src/openvpn/syshead.h
+++ b/src/openvpn/syshead.h
@@ -331,6 +331,10 @@
 #include <sys/mman.h>
 #endif
 
+#ifndef _WIN32
+#include <sys/utsname.h>
+#endif
+
 /*
  * Pedantic mode is meant to accomplish lint-style program checking,
  * not to build a working executable.