diff --git a/src/testdir/crash/double_free b/src/testdir/crash/double_free
new file mode 100644
index 0000000000..895c4a04b6
Binary files /dev/null and b/src/testdir/crash/double_free differ
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index fd786e5d54..29061aa423 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -190,6 +190,12 @@ func Test_crash1_3()
   call term_sendkeys(buf, args)
   call TermWait(buf, 150)
 
+  let file = 'crash/double_free'
+  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, 50)
+
   " clean up
   exe buf .. "bw!"
   bw!
diff --git a/src/version.c b/src/version.c
index 4dc9948d98..0e49ebd7a0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    647,
 /**/
     646,
 /**/
diff --git a/src/window.c b/src/window.c
index 7ca29d46a5..70c72bca75 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5837,10 +5837,7 @@ win_free(
     win_free_lsize(wp);
 
     for (i = 0; i < wp->w_tagstacklen; ++i)
-    {
-	vim_free(wp->w_tagstack[i].tagname);
-	vim_free(wp->w_tagstack[i].user_data);
-    }
+	tagstack_clear_entry(&wp->w_tagstack[i]);
     vim_free(wp->w_localdir);
     vim_free(wp->w_prevdir);