diff --git a/__tests__/custom-annotations.spec.ts b/__tests__/custom-annotations.spec.ts
index ff987c9..60d0db4 100644
--- a/__tests__/custom-annotations.spec.ts
+++ b/__tests__/custom-annotations.spec.ts
@@ -141,6 +141,14 @@ describe('custom and plugin annotation smoke checks', () => {
     expect(tableCopyBlock).toContain('function table.Copy(originalTable, lookupTable) end');
   });
 
+  test('derma.DefineSkin accepts partial skin tables', () => {
+    const defineSkin = readCustom('derma.DefineSkin.lua');
+
+    expect(defineSkin).toContain(
+      '---@param skin Partial<SKIN> Table containing skin overrides. Missing values inherit from the Default skin.',
+    );
+  });
+
   test('source-backed VGUI lookup and creation overrides expose nil failure paths', () => {
     const vguiLua = readOutput('vgui.lua');
     const createBlock = vguiLua.match(
diff --git a/custom/derma.DefineSkin.lua b/custom/derma.DefineSkin.lua
index 3fd35b3..fb09e67 100644
--- a/custom/derma.DefineSkin.lua
+++ b/custom/derma.DefineSkin.lua
@@ -5,5 +5,5 @@
 ---@[call_arg("gmod.derma_skin", "define")]
 ---@param name string Name of the skin.
 ---@param description string Description of the skin.
----@param skin SKIN Table containing skin data.
+---@param skin Partial<SKIN> Table containing skin overrides. Missing values inherit from the Default skin.
 function derma.DefineSkin(name, description, skin) end