diff --git a/lua/plenary/path.lua b/lua/plenary/path.lua
index 0865f2e3..fd8214c8 100644
--- a/lua/plenary/path.lua
+++ b/lua/plenary/path.lua
@@ -265,7 +265,7 @@ function Path:new(...)
   end
 
   local obj = {
-    filename = path_string,
+    filename = path_string:gsub("/", sep):gsub("\\", sep),
 
     _sep = sep,
   }
diff --git a/tests/plenary/path_spec.lua b/tests/plenary/path_spec.lua
index 0f02db04..853082a5 100644
--- a/tests/plenary/path_spec.lua
+++ b/tests/plenary/path_spec.lua
@@ -44,6 +44,10 @@ describe("Path", function()
     assert.are.same(Path:new("lua", "plenary"), Path:new("lua", Path:new "plenary"))
   end)
 
+  it("can join paths with different separators", function()
+    assert.are.same(Path:new("path\\to"):joinpath("lua/plenary"), Path:new("path/to/lua/plenary"))
+  end)
+
   it("inserts slashes", function()
     assert.are.same("lua" .. path.sep .. "plenary", Path:new("lua", "plenary").filename)
   end)