diff --git a/striker-ui/components/InputWithRef.tsx b/striker-ui/components/InputWithRef.tsx
index eb3bf9e2..06b532b9 100644
--- a/striker-ui/components/InputWithRef.tsx
+++ b/striker-ui/components/InputWithRef.tsx
@@ -12,7 +12,9 @@ import createInputOnChangeHandler, {
   MapToStateSetter,
 } from '../lib/createInputOnChangeHandler';
 
-type InputWithRefOptionalProps<TypeName extends keyof MapToType> = {
+type InputWithRefTypeMap = Pick<MapToType, 'number' | 'string'>;
+
+type InputWithRefOptionalProps<TypeName extends keyof InputWithRefTypeMap> = {
   createInputOnChangeHandlerOptions?: Omit<
     CreateInputOnChangeHandlerOptions<TypeName>,
     'set'
@@ -21,22 +23,21 @@ type InputWithRefOptionalProps<TypeName extends keyof MapToType> = {
 };
 
 type InputWithRefProps<
-  TypeName extends keyof MapToType,
+  TypeName extends keyof InputWithRefTypeMap,
   InputComponent extends ReactElement,
 > = InputWithRefOptionalProps<TypeName> & {
   input: InputComponent;
 };
 
-type InputForwardedRefContent<TypeName extends keyof MapToType> = {
+type InputForwardedRefContent<TypeName extends keyof InputWithRefTypeMap> = {
   getIsChangedByUser?: () => boolean;
-  getValue?: () => MapToType[TypeName];
+  getValue?: () => InputWithRefTypeMap[TypeName];
   setValue?: MapToStateSetter[TypeName];
 };
 
-const MAP_TO_INITIAL_VALUE: MapToType = {
+const MAP_TO_INITIAL_VALUE: InputWithRefTypeMap = {
   number: 0,
   string: '',
-  undefined,
 };
 
 const INPUT_WITH_REF_DEFAULT_PROPS: Required<
@@ -47,7 +48,10 @@ const INPUT_WITH_REF_DEFAULT_PROPS: Required<
 };
 
 const InputWithRef = forwardRef(
-  <TypeName extends keyof MapToType, InputComponent extends ReactElement>(
+  <
+    TypeName extends keyof InputWithRefTypeMap,
+    InputComponent extends ReactElement,
+  >(
     {
       createInputOnChangeHandlerOptions: {
         postSet: postSetAppend,
@@ -62,9 +66,9 @@ const InputWithRef = forwardRef(
       props: { onChange: initOnChange, value: initValue, ...restInitProps },
     } = input;
 
-    const [value, setValue] = useState<MapToType[TypeName]>(
+    const [value, setValue] = useState<InputWithRefTypeMap[TypeName]>(
       initValue ?? MAP_TO_INITIAL_VALUE[valueType],
-    ) as [MapToType[TypeName], MapToStateSetter[TypeName]];
+    ) as [InputWithRefTypeMap[TypeName], MapToStateSetter[TypeName]];
     const [isChangedByUser, setIsChangedByUser] = useState<boolean>(false);
 
     const onChange = createInputOnChangeHandler<TypeName>({
diff --git a/striker-ui/lib/createInputOnChangeHandler.ts b/striker-ui/lib/createInputOnChangeHandler.ts
index 5d3ac920..1103dbc6 100644
--- a/striker-ui/lib/createInputOnChangeHandler.ts
+++ b/striker-ui/lib/createInputOnChangeHandler.ts
@@ -3,15 +3,21 @@ import { Dispatch, SetStateAction } from 'react';
 
 import MAP_TO_VALUE_CONVERTER from './consts/MAP_TO_VALUE_CONVERTER';
 
+type CreateInputOnChangeHandlerTypeMap = Pick<MapToType, 'number' | 'string'>;
+
 type InputOnChangeParameters = Parameters<
   Exclude<MUIInputProps['onChange'], undefined>
 >;
 
 type MapToStateSetter = {
-  [TypeName in keyof MapToType]: Dispatch<SetStateAction<MapToType[TypeName]>>;
+  [TypeName in keyof CreateInputOnChangeHandlerTypeMap]: Dispatch<
+    SetStateAction<CreateInputOnChangeHandlerTypeMap[TypeName]>
+  >;
 };
 
-type CreateInputOnChangeHandlerOptions<TypeName extends keyof MapToType> = {
+type CreateInputOnChangeHandlerOptions<
+  TypeName extends keyof CreateInputOnChangeHandlerTypeMap,
+> = {
   postSet?: (...args: InputOnChangeParameters) => void;
   preSet?: (...args: InputOnChangeParameters) => void;
   set?: MapToStateSetter[TypeName];
@@ -19,7 +25,7 @@ type CreateInputOnChangeHandlerOptions<TypeName extends keyof MapToType> = {
 };
 
 const createInputOnChangeHandler =
-  <TypeName extends keyof MapToType>({
+  <TypeName extends keyof CreateInputOnChangeHandlerTypeMap>({
     postSet,
     preSet,
     set,
@@ -31,7 +37,7 @@ const createInputOnChangeHandler =
     } = event;
     const postConvertValue = MAP_TO_VALUE_CONVERTER[setType](
       value,
-    ) as MapToType[TypeName];
+    ) as CreateInputOnChangeHandlerTypeMap[TypeName];
 
     preSet?.call(null, event);
     set?.call(null, postConvertValue);
diff --git a/striker-ui/lib/isEmpty.ts b/striker-ui/lib/isEmpty.ts
index 5e3f3608..d2fd1970 100644
--- a/striker-ui/lib/isEmpty.ts
+++ b/striker-ui/lib/isEmpty.ts
@@ -1,6 +1,8 @@
+type IsEmptyTypeMap = Pick<MapToType, 'number' | 'string' | 'undefined'>;
+
 type MapToValueIsEmptyFunction = {
-  [TypeName in keyof MapToType]: (
-    value: MapToType[TypeName] | undefined,
+  [TypeName in keyof IsEmptyTypeMap]: (
+    value: IsEmptyTypeMap[TypeName],
   ) => boolean;
 };
 
@@ -10,8 +12,8 @@ const MAP_TO_VALUE_IS_EMPTY_FUNCTION: MapToValueIsEmptyFunction = {
   undefined: () => true,
 };
 
-const isEmpty = <TypeName extends keyof MapToType>(
-  values: Array<MapToType[TypeName] | undefined>,
+const isEmpty = <TypeName extends keyof IsEmptyTypeMap>(
+  values: Array<IsEmptyTypeMap[TypeName]>,
   { not, fn = 'every' }: { not?: boolean; fn?: 'every' | 'some' } = {},
 ): boolean =>
   values[fn]((value) => {