diff --git a/src/testdir/term_util.vim b/src/testdir/term_util.vim
index d748ed0..dac5a72 100644
--- a/src/testdir/term_util.vim
+++ b/src/testdir/term_util.vim
@@ -189,4 +189,43 @@
   return join(map(a:lines, 'term_getline(a:buf, v:val)'), '')
 endfunc
 
+" When using RunVimInTerminal() we expect modifyOtherKeys level 2 to be enabled
+" automatically.  The key + modifier Escape codes must then use the
+" modifyOtherKeys encoding.  They are recognized anyway, thus it's safer to use
+" than the raw code.
+
+" Return the modifyOtherKeys level 2 encoding for "key" with "modifier"
+" (number value, e.g. CTRL is 5).
+func GetEscCodeCSI27(key, modifier)
+  let key = printf("%d", char2nr(a:key))
+  let mod = printf("%d", a:modifier)
+  return "\<Esc>[27;" .. mod .. ';' .. key .. '~'
+endfunc
+
+" Return the modifyOtherKeys level 2 encoding for "key" with "modifier"
+" (character value, e.g. CTRL is "C").
+func GetEscCodeWithModifier(modifier, key)
+  let modifier = get({'C': 5}, a:modifier, '')
+  if modifier == ''
+    echoerr 'Unknown modifier: ' .. a:modifier
+  endif
+  return GetEscCodeCSI27(a:key, modifier)
+endfunc
+
+" Return the kitty keyboard protocol encoding for "key" with "modifier"
+" (number value, e.g. CTRL is 5).
+func GetEscCodeCSIu(key, modifier)
+  let key = printf("%d", char2nr(a:key))
+  let mod = printf("%d", a:modifier)
+  return "\<Esc>[" .. key .. ';' .. mod .. 'u'
+endfunc
+
+" Return the kitty keyboard protocol encoding for "key" without a modifier.
+" Used for the Escape key.
+func GetEscCodeCSIuWithoutModifier(key)
+  let key = printf("%d", char2nr(a:key))
+  return "\<Esc>[" .. key .. 'u'
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index 4ecdac6..0390d4f 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -584,7 +584,7 @@
   END
   call writefile(lines, 'XtestExprMap', 'D')
   let buf = RunVimInTerminal('-S XtestExprMap', #{rows: 10})
-  call term_sendkeys(buf, "\<C-B>")
+  call term_sendkeys(buf, GetEscCodeWithModifier('C', 'B'))
   call VerifyScreenDump(buf, 'Test_map_expr_1', {})
 
   " clean up
diff --git a/src/testdir/test_popupwin.vim b/src/testdir/test_popupwin.vim
index 0f7f18c9..2aebea4 100644
--- a/src/testdir/test_popupwin.vim
+++ b/src/testdir/test_popupwin.vim
@@ -4,6 +4,7 @@
 CheckFeature popupwin
 
 source screendump.vim
+source term_util.vim
 
 func Test_simple_popup()
   CheckScreendump
@@ -3722,7 +3723,9 @@
   let buf = RunVimInTerminal('-S XtestPopupmenuMasking', #{rows: 14})
   call TermWait(buf, 25)
 
-  call term_sendkeys(buf, "A\<C-X>\<C-U>\<C-A>")
+  call term_sendkeys(buf, "A" .. GetEscCodeWithModifier('C', 'X')
+			    \ .. GetEscCodeWithModifier('C', 'U')
+			    \ .. GetEscCodeWithModifier('C', 'A'))
   call VerifyScreenDump(buf, 'Test_popupwin_popupmenu_masking_1', {})
 
   call term_sendkeys(buf, "\<Esc>")
diff --git a/src/testdir/test_termcodes.vim b/src/testdir/test_termcodes.vim
index a9a19e8..690a3f7 100644
--- a/src/testdir/test_termcodes.vim
+++ b/src/testdir/test_termcodes.vim
@@ -2094,23 +2094,6 @@
   call StopVimInTerminal('')
 endfunc
 
-func GetEscCodeCSI27(key, modifier)
-  let key = printf("%d", char2nr(a:key))
-  let mod = printf("%d", a:modifier)
-  return "\<Esc>[27;" .. mod .. ';' .. key .. '~'
-endfunc
-
-func GetEscCodeCSIu(key, modifier)
-  let key = printf("%d", char2nr(a:key))
-  let mod = printf("%d", a:modifier)
-  return "\<Esc>[" .. key .. ';' .. mod .. 'u'
-endfunc
-
-func GetEscCodeCSIuWithoutModifier(key)
-  let key = printf("%d", char2nr(a:key))
-  return "\<Esc>[" .. key .. 'u'
-endfunc
-
 " This checks the CSI sequences when in modifyOtherKeys mode.
 " The mode doesn't need to be enabled, the codes are always detected.
 func RunTest_modifyOtherKeys(func)
diff --git a/src/version.c b/src/version.c
index 33f736a..a00a989 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    956,
+/**/
     955,
 /**/
     954,