diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index ce30b8d..0d76b3b 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -197,9 +197,11 @@
 	// restore to empty when write failed
 	if (empty_bufname)
 	{
-	    VIM_CLEAR(buf->b_fname);
+	    // prevent double free
+	    if (buf->b_sfname != buf->b_ffname)
+		VIM_CLEAR(buf->b_sfname);
+	    buf->b_fname = NULL;
 	    VIM_CLEAR(buf->b_ffname);
-	    VIM_CLEAR(buf->b_sfname);
 	    unchanged(buf, TRUE, FALSE);
 	}
     }
diff --git a/src/testdir/crash/dialog_changed_uaf b/src/testdir/crash/dialog_changed_uaf
new file mode 100644
index 0000000..e37d18d
--- /dev/null
+++ b/src/testdir/crash/dialog_changed_uaf
Binary files differ
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index 29061aa..9aef245 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -196,6 +196,12 @@
   call term_sendkeys(buf, args)
   call TermWait(buf, 50)
 
+  let file = 'crash/dialog_changed_uaf'
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args)
+  call TermWait(buf, 150)
+
   " clean up
   exe buf .. "bw!"
   bw!
diff --git a/src/version.c b/src/version.c
index 0e49ebd..3ca6001 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    648,
+/**/
     647,
 /**/
     646,