Change setTheme type to React.Dispatch<React.SetStateAction<string>>.

src/index.tsx

@@ -81,15 +81,22 @@ const Theme: React.FC<ThemeProviderProps> = ({
   }, [])
 
   const setTheme = useCallback(
-    theme => {
-      setThemeState(theme)
-
-      // Save to storage
-      try {
-        localStorage.setItem(storageKey, theme)
-      } catch (e) {
-        // Unsupported
-      }
+    (newTheme: React.SetStateAction<string>) => {
+
+      setThemeState(
+        prevTheme => {
+          const _theme = (newTheme instanceof Function) ? newTheme(prevTheme ?? defaultTheme) : prevTheme ?? defaultTheme;
+
+          // Save to storage
+          try {
+            localStorage.setItem(storageKey, _theme)
+          } catch (e) {
+            // Unsupported
+          }
+
+          return _theme
+        }
+      )
     },
     [forcedTheme]
   )

src/types.ts

@@ -8,7 +8,7 @@ export interface UseThemeProps {
   /** Forced theme name for the current page */
   forcedTheme?: string
   /** Update the theme */
-  setTheme: (theme: string) => void
+  setTheme: React.Dispatch<React.SetStateAction<string>>
   /** Active theme name */
   theme?: string
   /** If `enableSystem` is true and the active theme is "system", this returns whether the system preference resolved to "dark" or "light". Otherwise, identical to `theme` */