diff --git a/addons/knobs/src/components/types/Number.tsx b/addons/knobs/src/components/types/Number.tsx
index 7778976f0e24..bfd0318a61b0 100644
--- a/addons/knobs/src/components/types/Number.tsx
+++ b/addons/knobs/src/components/types/Number.tsx
@@ -14,11 +14,8 @@ export interface NumberTypeKnobOptions {
   step?: number;
 }
 
-export interface NumberTypeKnob
-  extends KnobControlConfig<NumberTypeKnobValue>,
-    NumberTypeKnobOptions {
-  value: NumberTypeKnobValue;
-}
+export type NumberTypeKnob = KnobControlConfig<NumberTypeKnobValue> &
+  NumberTypeKnobOptions & { value?: NumberTypeKnobValue };
 
 interface NumberTypeProps extends KnobControlProps<NumberTypeKnobValue | null> {
   knob: NumberTypeKnob;
diff --git a/addons/knobs/src/components/types/Text.tsx b/addons/knobs/src/components/types/Text.tsx
index f09c8b526ca9..c0525a606676 100644
--- a/addons/knobs/src/components/types/Text.tsx
+++ b/addons/knobs/src/components/types/Text.tsx
@@ -5,7 +5,7 @@ import { Form } from '@storybook/components';
 import { KnobControlConfig, KnobControlProps } from './types';
 
 type TextTypeKnobValue = string;
-export type TextTypeKnob = KnobControlConfig<TextTypeKnobValue>;
+export type TextTypeKnob = KnobControlConfig<TextTypeKnobValue> & { value?: TextTypeKnobValue };
 type TextTypeProps = KnobControlProps<TextTypeKnobValue>;
 
 export default class TextType extends Component<TextTypeProps> {