diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index 9bc0238672..8af4796a61 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -2253,7 +2253,7 @@ void f_mapset(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
   // Delete any existing mapping for this lhs and mode.
   MapArguments unmap_args = MAP_ARGUMENTS_INIT;
-  set_maparg_lhs_rhs(lhs, strlen(lhs), "", 0, LUA_NOREF, 0, &unmap_args);
+  set_maparg_lhs_rhs(lhs, strlen(lhs), "", 0, LUA_NOREF, CPO_TO_CPO_FLAGS, &unmap_args);
   unmap_args.buffer = buffer;
   buf_do_map(MAPTYPE_UNMAP, &unmap_args, mode, is_abbr, curbuf);
   xfree(unmap_args.rhs);
diff --git a/test/functional/vimscript/map_functions_spec.lua b/test/functional/vimscript/map_functions_spec.lua
index ba1b4d7a76..ec7a21f35b 100644
--- a/test/functional/vimscript/map_functions_spec.lua
+++ b/test/functional/vimscript/map_functions_spec.lua
@@ -174,6 +174,16 @@ end)
 describe('mapset()', function()
   before_each(clear)
 
+  it('can restore mapping with backslash in lhs', function()
+    meths.set_keymap('n', '\\ab', 'a', {})
+    eq('\nn  \\ab           a', exec_capture("nmap \\ab"))
+    local mapargs = funcs.maparg('\\ab', 'n', false, true)
+    meths.set_keymap('n', '\\ab', 'b', {})
+    eq('\nn  \\ab           b', exec_capture("nmap \\ab"))
+    funcs.mapset('n', false, mapargs)
+    eq('\nn  \\ab           a', exec_capture("nmap \\ab"))
+  end)
+
   it('can restore mapping description from the dict returned by maparg()', function()
     meths.set_keymap('n', 'lhs', 'rhs', {desc = 'map description'})
     eq('\nn  lhs           rhs\n                 map description', exec_capture("nmap lhs"))