diff --git a/src/Theme/index.ts b/src/Theme/index.ts
index 8b161ce..552168b 100644
--- a/src/Theme/index.ts
+++ b/src/Theme/index.ts
@@ -36,12 +36,14 @@ const generateTheme = (options: {
   themes: ThemeInput[];
   generateColorShades?: boolean | ShadesOptions;
 }) => {
+  let themes = options.themes;
+
   if (
     options.generateColorShades !== undefined &&
     options.generateColorShades !== false
   ) {
-    options.themes = options.themes.map((theme) => {
-      theme.colors = {
+    themes = themes.map((theme) => {
+      const updatedColors = {
         ...generateShades(
           theme.colors,
           typeof options.generateColorShades !== "boolean"
@@ -51,16 +53,16 @@ const generateTheme = (options: {
         ...theme.colors,
       };
 
-      return theme;
+      return { ...theme, colors: updatedColors };
     });
   }
 
   const themeRoot = generateThemeRoot({
-    properties: { ...options.themes[0].colors },
+    properties: { ...themes[0].colors },
   });
 
-  if (options.themes.length > 1) {
-    const themeOverrides = options.themes
+  if (themes.length > 1) {
+    const themeOverrides = themes
       .slice(1)
       .map((theme) => {
         const overrideClass = generateThemeOverrideClass({