diff --git a/components/tools/ManipulationPanel.tsx b/components/tools/ManipulationPanel.tsx
index c9e7def..52b41af 100644
--- a/components/tools/ManipulationPanel.tsx
+++ b/components/tools/ManipulationPanel.tsx
@@ -33,11 +33,11 @@ export function ManipulationPanel({ color, onColorChange }: ManipulationPanelPro
   const complementMutation = useComplement();
 
   // Debounce timers
-  const lightenTimer = useRef<NodeJS.Timeout>();
-  const darkenTimer = useRef<NodeJS.Timeout>();
-  const saturateTimer = useRef<NodeJS.Timeout>();
-  const desaturateTimer = useRef<NodeJS.Timeout>();
-  const rotateTimer = useRef<NodeJS.Timeout>();
+  const lightenTimer = useRef<NodeJS.Timeout | undefined>(undefined);
+  const darkenTimer = useRef<NodeJS.Timeout | undefined>(undefined);
+  const saturateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
+  const desaturateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
+  const rotateTimer = useRef<NodeJS.Timeout | undefined>(undefined);
 
   // Reactive lighten
   useEffect(() => {