diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
index ea1117a906..6eb7a970e4 100644
--- a/runtime/lua/vim/shared.lua
+++ b/runtime/lua/vim/shared.lua
@@ -20,6 +20,11 @@ vim.deepcopy = (function()
   local deepcopy_funcs = {
     table = function(orig)
       local copy = {}
+
+      if vim._empty_dict_mt ~= nil and getmetatable(orig) == vim._empty_dict_mt then
+        copy = vim.empty_dict()
+      end
+
       for k, v in pairs(orig) do
         copy[vim.deepcopy(k)] = vim.deepcopy(v)
       end
@@ -169,9 +174,19 @@ function vim.tbl_extend(behavior, ...)
   if (behavior ~= 'error' and behavior ~= 'keep' and behavior ~= 'force') then
     error('invalid "behavior": '..tostring(behavior))
   end
+
+  if select('#', ...) < 2 then
+    error('wrong number of arguments (given '..tostring(1 + select('#', ...))..', expected at least 3)')
+  end
+
   local ret = {}
+  if vim._empty_dict_mt ~= nil and getmetatable(select(1, ...)) == vim._empty_dict_mt then
+    ret = vim.empty_dict()
+  end
+
   for i = 1, select('#', ...) do
     local tbl = select(i, ...)
+    vim.validate{["after the second argument"] = {tbl,'t'}}
     if tbl then
       for k, v in pairs(tbl) do
         if behavior ~= 'force' and ret[k] ~= nil then
diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index 339fbd65a0..ca7c5301ed 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -7,6 +7,7 @@ local meths = helpers.meths
 local command = helpers.command
 local clear = helpers.clear
 local eq = helpers.eq
+local ok = helpers.ok
 local eval = helpers.eval
 local feed = helpers.feed
 local pcall_err = helpers.pcall_err
@@ -310,7 +311,7 @@ describe('lua stdlib', function()
   end)
 
   it("vim.deepcopy", function()
-    local is_dc = exec_lua([[
+    ok(exec_lua([[
       local a = { x = { 1, 2 }, y = 5}
       local b = vim.deepcopy(a)
 
@@ -319,9 +320,39 @@ describe('lua stdlib', function()
 
       return b.x[1] == 1 and b.x[2] == 2 and b.y == 5 and count == 2
              and tostring(a) ~= tostring(b)
-    ]])
+    ]]))
 
-    assert(is_dc)
+    ok(exec_lua([[
+      local a = {}
+      local b = vim.deepcopy(a)
+
+      local count = 0
+      for _ in pairs(b) do count = count + 1 end
+
+      return vim.tbl_islist(b) and count == 0 and tostring(a) ~= tostring(b)
+    ]]))
+
+    ok(exec_lua([[
+      local a = vim.empty_dict()
+      local b = vim.deepcopy(a)
+
+      local count = 0
+      for _ in pairs(b) do count = count + 1 end
+
+      return not vim.tbl_islist(b) and count == 0
+    ]]))
+
+    ok(exec_lua([[
+      local a = {x = vim.empty_dict(), y = {}}
+      local b = vim.deepcopy(a)
+
+      local count = 0
+      for _ in pairs(b) do count = count + 1 end
+
+      return not vim.tbl_islist(b.x) and vim.tbl_islist(b.y)
+        and count == 2
+        and tostring(a) ~= tostring(b)
+    ]]))
   end)
 
   it('vim.pesc', function()
@@ -369,6 +400,93 @@ describe('lua stdlib', function()
     eq(false, exec_lua("return vim.tbl_isempty({a=1, b=2, c=3})"))
   end)
 
+  it('vim.tbl_extend', function()
+    ok(exec_lua([[
+      local a = {x = 1}
+      local b = {y = 2}
+      local c = vim.tbl_extend("keep", a, b)
+
+      local count = 0
+      for _ in pairs(c) do count = count + 1 end
+
+      return c.x == 1 and b.y == 2 and count == 2
+    ]]))
+
+    ok(exec_lua([[
+      local a = {x = 1}
+      local b = {y = 2}
+      local c = {z = 3}
+      local d = vim.tbl_extend("keep", a, b, c)
+
+      local count = 0
+      for _ in pairs(d) do count = count + 1 end
+
+      return d.x == 1 and d.y == 2 and d.z == 3 and count == 3
+    ]]))
+
+    ok(exec_lua([[
+      local a = {x = 1}
+      local b = {x = 3}
+      local c = vim.tbl_extend("keep", a, b)
+
+      local count = 0
+      for _ in pairs(c) do count = count + 1 end
+
+      return c.x == 1 and count == 1
+    ]]))
+
+    ok(exec_lua([[
+      local a = {x = 1}
+      local b = {x = 3}
+      local c = vim.tbl_extend("force", a, b)
+
+      local count = 0
+      for _ in pairs(c) do count = count + 1 end
+
+      return c.x == 3 and count == 1
+    ]]))
+
+    ok(exec_lua([[
+      local a = vim.empty_dict()
+      local b = {}
+      local c = vim.tbl_extend("keep", a, b)
+
+      local count = 0
+      for _ in pairs(c) do count = count + 1 end
+
+      return not vim.tbl_islist(c) and count == 0
+    ]]))
+
+    ok(exec_lua([[
+      local a = {}
+      local b = vim.empty_dict()
+      local c = vim.tbl_extend("keep", a, b)
+
+      local count = 0
+      for _ in pairs(c) do count = count + 1 end
+
+      return vim.tbl_islist(c) and count == 0
+    ]]))
+
+    eq('Error executing lua: .../shared.lua: invalid "behavior": nil',
+      pcall_err(exec_lua, [[
+        return vim.tbl_extend()
+      ]])
+    )
+
+    eq('Error executing lua: .../shared.lua: wrong number of arguments (given 1, expected at least 3)',
+      pcall_err(exec_lua, [[
+        return vim.tbl_extend("keep")
+      ]])
+    )
+
+    eq('Error executing lua: .../shared.lua: wrong number of arguments (given 2, expected at least 3)',
+      pcall_err(exec_lua, [[
+        return vim.tbl_extend("keep", {})
+      ]])
+    )
+  end)
+
   it('vim.deep_equal', function()
     eq(true, exec_lua [[ return vim.deep_equal({a=1}, {a=1}) ]])
     eq(true, exec_lua [[ return vim.deep_equal({a={b=1}}, {a={b=1}}) ]])