diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 5a52d37577..1188b72821 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -2052,7 +2052,7 @@ static void calculate_topfill_and_topline(const int fromidx, const int toidx, co
 
   // move the same amount of virtual lines in the target buffer to find the
   // cursor's line number
-  int curlinenum_to = thistopdiff->df_lnum[toidx];
+  int curlinenum_to = thistopdiff != NULL ? thistopdiff->df_lnum[toidx] : 1;
 
   int virt_lines_left = virtual_lines_passed;
   curdif = thistopdiff;
diff --git a/test/old/testdir/shared.vim b/test/old/testdir/shared.vim
index bb1a6c8f5b..cefca1c2e6 100644
--- a/test/old/testdir/shared.vim
+++ b/test/old/testdir/shared.vim
@@ -211,11 +211,11 @@ func s:WaitForCommon(expr, assert, timeout)
       call remove(v:errors, -1)
     endif
 
-    sleep 10m
+    sleep 1m
     if exists('*reltimefloat')
       let slept = float2nr(reltimefloat(reltime(start)) * 1000)
     else
-      let slept += 10
+      let slept += 1
     endif
   endwhile
 
diff --git a/test/old/testdir/test_crash.vim b/test/old/testdir/test_crash.vim
index 5ddbd07b55..88713894d1 100644
--- a/test/old/testdir/test_crash.vim
+++ b/test/old/testdir/test_crash.vim
@@ -4,11 +4,15 @@ source screendump.vim
 
 CheckScreendump
 
+" Run the command in terminal and wait for it to complete via notification
+func s:RunCommandAndWait(buf, cmd)
+  call term_sendkeys(a:buf, a:cmd .. "; printf '" .. TermNotifyParentCmd(v:false) .. "'\<cr>")
+  call WaitForChildNotification()
+endfunc
+
 func Test_crash1()
   CheckNotBSD
   CheckExecutable dash
-  " Test 7 fails on Mac ...
-  CheckNotMac
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -19,70 +23,59 @@ func Test_crash1()
   let file = 'crash/poc_huaf1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt')
 
   let file = 'crash/poc_huaf2'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/poc_huaf3'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 100)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/bt_quickfix_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('Xerr')
-  " This test takes a bit longer
-  call TermWait(buf, 1000)
 
   let file = 'crash/poc_tagfunc.vim'
   let args = printf(cmn_args, vim, file)
   " using || because this poc causes vim to exit with exitstatus != 0
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt')
 
-  call TermWait(buf, 100)
 
   let file = 'crash/bt_quickfix1_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('X')
-  call TermWait(buf, 3000)
 
   let file = 'crash/vim_regsub_both_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/vim_msg_trunc_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/crash_scrollbar'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/editing_arg_idx_POC_1'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt')
   call delete('Xerr')
   call delete('@')
 
@@ -113,7 +106,6 @@ endfunc
 func Test_crash1_2()
   CheckNotBSD
   CheckExecutable dash
-  let g:test_is_flaky = 1
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -125,37 +117,54 @@ func Test_crash1_2()
   let file = 'crash/poc1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > '.. result)
 
   let file = 'crash/poc_win_enter_ext'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 350)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> '.. result)
 
   let file = 'crash/poc_suggest_trie_walk'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> '.. result)
 
   let file = 'crash/poc_did_set_langmap'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 4: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 4: [OK]" >> '.. result)
 
   let file = 'crash/reverse_text_overflow'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 5: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 5: [OK]" >> '.. result)
+
+  let file = 'Xdiff'
+  let lines =<< trim END
+    diffs a
+    edit Xdiff
+    file b
+    exe "norm! \<C-w>\<C-w>"
+    exe "norm! \<C-w>\<C-w>"
+    exe "norm! \<C-w>\<C-w>"
+    exe "norm! \<C-w>\<C-w>"
+    exe "norm! \<C-w>\<C-w>"
+    exe "norm! \<C-w>\L"
+    exe "norm! \<C-j>oy\<C-j>"
+    edit Xdiff
+    sil!so
+  END
+  call writefile(lines, file, 'D')
+  let cmn_args = "%s -u NONE -i NONE -X -m -n -e -s -u %s -c ':qa!'"
+  let args = printf(cmn_args, vim, file)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' && echo "crash 6: [OK]" >> '.. result)
+
 
   " clean up
   exe buf .. "bw!"
@@ -166,6 +175,7 @@ func Test_crash1_2()
       \ 'crash 3: [OK]',
       \ 'crash 4: [OK]',
       \ 'crash 5: [OK]',
+      \ 'crash 6: [OK]',
       \ ]
 
   call assert_equal(expected, getline(1, '$'))