diff --git a/packages/primevue/src/steppanel/StepPanel.d.ts b/packages/primevue/src/steppanel/StepPanel.d.ts
index 2cf8d6412..b86d57496 100644
--- a/packages/primevue/src/steppanel/StepPanel.d.ts
+++ b/packages/primevue/src/steppanel/StepPanel.d.ts
@@ -117,7 +117,7 @@ export interface StepPanelSlots {
         /**
          * Click function.
          */
-        activateCallback: (value?: string | number) => void;
+        activateCallback: (value: string | number) => void;
     }): VNode[];
 }