diff --git a/unix/gtkwin.c b/unix/gtkwin.c
index ad8ade52..667c72b3 100644
--- a/unix/gtkwin.c
+++ b/unix/gtkwin.c
@@ -3344,7 +3344,6 @@ int read_dupsession_data(struct gui_data *inst, Conf *conf, char *arg)
     }
 
     size_used = conf_deserialise(conf, data, size);
-    sfree(data);
     if (use_pty_argv && size > size_used) {
 	int n = 0;
 	i = size_used;
@@ -3371,6 +3370,8 @@ int read_dupsession_data(struct gui_data *inst, Conf *conf, char *arg)
 	}
     }
 
+    sfree(data);
+
     return 0;
 }