diff --git a/src/xterm.c b/src/xterm.c
index 0d2452de92..05353a2ec2 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -12927,24 +12927,19 @@ #define NUM_ARGV 10
   XSetAfterFunction (x_current_display, x_trace_wire);
 #endif
 
-  Lisp_Object system_name = Fsystem_name ();
   static char const title[] = "GNU Emacs";
+  static char const at[] = " at ";
+  Lisp_Object system_name = Fsystem_name ();
+  ptrdiff_t nbytes = sizeof (title) + sizeof (at);
+  if (STRINGP (system_name)
+      && INT_ADD_WRAPV (nbytes, SBYTES (system_name) + 1, &nbytes))
+    memory_full (SIZE_MAX);
+  dpyinfo->x_id = ++x_display_id;
+  dpyinfo->x_id_name = xmalloc (nbytes);
   if (STRINGP (system_name))
-    {
-      static char const at[] = " at ";
-      ptrdiff_t nbytes = sizeof (title) + sizeof (at);
-      if (INT_ADD_WRAPV (nbytes, SBYTES (system_name), &nbytes))
-	memory_full (SIZE_MAX);
-      dpyinfo->x_id_name = xmalloc (nbytes);
       sprintf (dpyinfo->x_id_name, "%s%s%s", title, at, SDATA (system_name));
-    }
   else
-    {
-      dpyinfo->x_id_name = xmalloc (sizeof (title));
       strcpy (dpyinfo->x_id_name, title);
-    }
-
-  dpyinfo->x_id = ++x_display_id;
 
   /* Figure out which modifier bits mean what.  */
   x_find_modifier_meanings (dpyinfo);