diff --git a/src/drawscreen.c b/src/drawscreen.c
index 852d331..5fb37a9 100644
--- a/src/drawscreen.c
+++ b/src/drawscreen.c
@@ -1537,7 +1537,7 @@
 
     // Make sure skipcol is valid, it depends on various options and the window
     // width.
-    if (wp->w_skipcol > 0)
+    if (wp->w_skipcol > 0 && wp->w_width > win_col_off(wp))
     {
 	int w = 0;
 	int width1 = wp->w_width - win_col_off(wp);
diff --git a/src/proto/window.pro b/src/proto/window.pro
index 0ec5734..a91a511 100644
--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -28,7 +28,7 @@
 void may_trigger_win_scrolled_resized(void);
 void win_close_othertab(win_T *win, int free_buf, tabpage_T *tp);
 void win_free_all(void);
-win_T *winframe_remove(win_T *win, int *dirp, tabpage_T *tp, frame_T **to_flatten);
+win_T *winframe_remove(win_T *win, int *dirp, tabpage_T *tp, frame_T **unflat_altfr);
 void close_others(int message, int forceit);
 void unuse_tabpage(tabpage_T *tp);
 void use_tabpage(tabpage_T *tp);
diff --git a/src/testdir/test_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index f41f0e2..3467760 100644
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -960,4 +960,42 @@
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_smoothscroll_in_zero_width_window()
+  set cpo+=n number smoothscroll
+  set winwidth=99999 winminwidth=0
+
+  vsplit
+  call assert_equal(0, winwidth(winnr('#')))
+  call win_execute(win_getid(winnr('#')), "norm! \<C-Y>")
+
+  only!
+  set winwidth& winminwidth&
+  set cpo-=n nonumber nosmoothscroll
+endfunc
+
+func Test_smoothscroll_textoff_small_winwidth()
+  set smoothscroll number
+  call setline(1, 'llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch')
+  vsplit
+
+  let textoff = getwininfo(win_getid())[0].textoff
+  execute 'vertical resize' textoff + 1
+  redraw
+  call assert_equal(0, winsaveview().skipcol)
+  execute "normal! 0\<C-E>"
+  redraw
+  call assert_equal(1, winsaveview().skipcol)
+  execute 'vertical resize' textoff - 1
+  " This caused a signed integer overflow.
+  redraw
+  call assert_equal(1, winsaveview().skipcol)
+  execute 'vertical resize' textoff
+  " This caused an infinite loop.
+  redraw
+  call assert_equal(1, winsaveview().skipcol)
+
+  %bw!
+  set smoothscroll& number&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_window_cmd.vim b/src/testdir/test_window_cmd.vim
index ff4ab84..a68ed74 100644
--- a/src/testdir/test_window_cmd.vim
+++ b/src/testdir/test_window_cmd.vim
@@ -322,14 +322,18 @@
   call assert_equal(restcmd, winrestcmd())
 
   " Check that the last statusline isn't lost.
-  set laststatus=0
-  let restcmd = winrestcmd()
+  " Set its window's width to 2 for the test.
   wincmd j
+  set laststatus=0 winminwidth=0
+  vertical resize 2
+  set winminwidth&
   call setwinvar(winnr('k'), '&statusline', '@#')
   let last_stl_row = win_screenpos(0)[0] - 1
   redraw
   call assert_equal('@#|', GetScreenStr(last_stl_row))
   call assert_equal('~ |', GetScreenStr(&lines - &cmdheight))
+
+  let restcmd = winrestcmd()
   call assert_fails('wincmd H', 'E36:')
   call assert_fails('wincmd L', 'E36:')
   call assert_equal(layout, winlayout())
@@ -2153,19 +2157,6 @@
   call assert_equal(expand("<cword>"), "'mod'")
 endfunc
 
-func Test_smoothscroll_in_zero_width_window()
-  set cpo+=n number smoothscroll
-  set winwidth=99999 winminwidth=0
-
-  vsplit
-  call assert_equal(0, winwidth(winnr('#')))
-  call win_execute(win_getid(winnr('#')), "norm! \<C-Y>")
-
-  only!
-  set winwidth& winminwidth&
-  set cpo-=n nonumber nosmoothscroll
-endfunc
-
 func Test_splitmove_flatten_frame()
   split
   vsplit
@@ -2179,7 +2170,7 @@
   only!
 endfunc
 
-func Test_splitmove_autocmd_window_no_room()
+func Test_autocmd_window_force_room()
   " Open as many windows as possible
   while v:true
     try
@@ -2206,7 +2197,7 @@
   edit unload me
   enew
   bunload! unload\ me
-  augroup SplitMoveAucmdWin
+  augroup AucmdWinForceRoom
     au!
     au BufEnter * ++once let s:triggered = v:true
                       \| call assert_equal('autocmd', win_gettype())
@@ -2220,8 +2211,8 @@
   call assert_equal(winrestcmd(), restcmd)
 
   unlet! s:triggered
-  au! SplitMoveAucmdWin
-  augroup! SplitMoveAucmdWin
+  au! AucmdWinForceRoom
+  augroup! AucmdWinForceRoom
   %bw!
 endfunc
 
diff --git a/src/version.c b/src/version.c
index d495165..471ecd8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    121,
+/**/
     120,
 /**/
     119,
diff --git a/src/window.c b/src/window.c
index a6223ee..66a1d7d 100644
--- a/src/window.c
+++ b/src/window.c
@@ -54,7 +54,7 @@
 static void frame_add_height(frame_T *frp, int n);
 static void last_status_rec(frame_T *fr, int statusline);
 static void frame_flatten(frame_T *frp);
-static void winframe_restore(win_T *wp, int dir, frame_T *to_flatten);
+static void winframe_restore(win_T *wp, int dir, frame_T *unflat_altfr);
 
 static int make_snapshot_rec(frame_T *fr, frame_T **frp);
 static void clear_snapshot(tabpage_T *tp, int idx);