diff --git a/packages/pigment-css-unplugin/src/index.ts b/packages/pigment-css-unplugin/src/index.ts
index 6ae7addc..39868621 100644
--- a/packages/pigment-css-unplugin/src/index.ts
+++ b/packages/pigment-css-unplugin/src/index.ts
@@ -91,6 +91,7 @@ const addMaterialUIOverriedContext = (originalContext: Record<string, unknown>)
         __esModule: true,
         default: () => () => () => null,
         internal_processStyles: () => {},
+        internal_serializeStyles: () => {},
         keyframes: () => '',
         css: () => '',
       };
diff --git a/packages/pigment-css-vite-plugin/src/vite-plugin.ts b/packages/pigment-css-vite-plugin/src/vite-plugin.ts
index 02580197..ad5e72c3 100644
--- a/packages/pigment-css-vite-plugin/src/vite-plugin.ts
+++ b/packages/pigment-css-vite-plugin/src/vite-plugin.ts
@@ -49,6 +49,7 @@ const addMaterialUIOverriedContext = (originalContext: Record<string, unknown>)
         __esModule: true,
         default: () => () => () => null,
         internal_processStyles: () => {},
+        internal_serializeStyles: () => {},
         keyframes: () => '',
         css: () => '',
       };