diff --git a/src/testdir/mouse.vim b/src/testdir/mouse.vim
index 5eab1de..d59ad0e 100644
--- a/src/testdir/mouse.vim
+++ b/src/testdir/mouse.vim
@@ -103,6 +103,24 @@
   call feedkeys(MouseCtrlRightClickCode(a:row, a:col), 'Lx!')
 endfunc
 
+func MouseAltLeftClickCode(row, col)
+  let alt = 0x8
+  return TerminalEscapeCode(0 + alt, a:row, a:col, 'M')
+endfunc
+
+func MouseAltLeftClick(row, col)
+  call feedkeys(MouseAltLeftClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseAltRightClickCode(row, col)
+  let alt = 0x8
+  return TerminalEscapeCode(2 + alt, a:row, a:col, 'M')
+endfunc
+
+func MouseAltRightClick(row, col)
+  call feedkeys(MouseAltRightClickCode(a:row, a:col), 'Lx!')
+endfunc
+
 func MouseLeftReleaseCode(row, col)
   if &ttymouse ==# 'dec'
     return DecEscapeCode(3, 0, a:row, a:col)