diff -ur a/xdm/choose.c b/xdm/choose.c
--- a/xdm/choose.c	2011-09-25 09:35:47.000000000 +0200
+++ b/xdm/choose.c	2014-01-06 16:33:09.628065364 +0100
@@ -54,6 +54,14 @@
 #  include       <tiuser.h>
 # endif
 
+# ifdef HAVE_SETPROCTITLE
+#  ifdef __linux__
+#   include <bsd/unistd.h>
+#  else
+#   include <unistd.h>
+#  endif
+# endif
+
 # include <time.h>
 # define Time_t time_t
 
diff -ur a/xdm/session.c b/xdm/session.c
--- a/xdm/session.c	2011-09-25 09:35:47.000000000 +0200
+++ b/xdm/session.c	2014-01-06 16:40:57.508072789 +0100
@@ -54,6 +54,15 @@
 # include <usersec.h>
 #endif
 
+# ifdef HAVE_SETPROCTITLE
+#  include <sys/types.h>
+#  ifdef __linux__
+#   include <bsd/unistd.h>
+#  else
+#   include <unistd.h>
+#  endif
+# endif
+
 #ifndef USE_PAM        /* PAM modules should handle these */
 # ifdef SECURE_RPC
 #  include <rpc/rpc.h>