diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index 7bba24483e..7f10dcd8da 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -1079,34 +1079,21 @@ describe('lua stdlib', function()
       return vim.deep_equal(c, { sub = { [1] = 'a', b = 'a' } })
     ]]))
 
-    matches(
-      'invalid "behavior": nil',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend()
-      ]]
-      )
-    )
+    matches('invalid "behavior": nil', pcall_err(exec_lua, [[return vim.tbl_deep_extend()]]))
 
     matches(
       'wrong number of arguments %(given 1, expected at least 3%)',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend("keep")
-      ]]
-      )
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep")]])
     )
 
     matches(
       'wrong number of arguments %(given 2, expected at least 3%)',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend("keep", {})
-      ]]
-      )
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep", {})]])
+    )
+
+    matches(
+      'after the second argument%: expected table, got number',
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep", {}, 42)]])
     )
   end)