diff --git a/gbajs3/src/components/modals/save-states.tsx b/gbajs3/src/components/modals/save-states.tsx
index cd7dadbe..8f4e8077 100644
--- a/gbajs3/src/components/modals/save-states.tsx
+++ b/gbajs3/src/components/modals/save-states.tsx
@@ -122,9 +122,8 @@ export const SaveStatesModal = () => {
     setValue('saveStateSlot', currentSlot);
   }, [currentSlot, setValue]);
 
-  const onSubmit: SubmitHandler<InputProps> = async (formData) => {
+  const onSubmit: SubmitHandler<InputProps> = async (formData) =>
     setCurrentSlot(formData.saveStateSlot);
-  };
 
   const renderedSaveStates =
     currentSaveStates ??
diff --git a/gbajs3/src/components/shared/number-input.spec.tsx b/gbajs3/src/components/shared/number-input.spec.tsx
index 7b7274ab..83fd9197 100644
--- a/gbajs3/src/components/shared/number-input.spec.tsx
+++ b/gbajs3/src/components/shared/number-input.spec.tsx
@@ -1,9 +1,11 @@
 import { fireEvent, render, screen } from '@testing-library/react';
 import { userEvent } from '@testing-library/user-event';
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, vi } from 'vitest';
 
 import { NumberInput } from './number-input.tsx';
 
+import type { RefObject } from 'react';
+
 describe('<NumberInput />', () => {
   it('renders correctly with default props', () => {
     render(<NumberInput />);
@@ -60,7 +62,7 @@ describe('<NumberInput />', () => {
     expect(inputElement).toHaveValue(6);
   });
 
-  it('clamps value to min when empty', async () => {
+  it('clamps value to min when empty on blur', async () => {
     render(<NumberInput defaultValue="5" min={1} />);
 
     const inputElement = screen.getByRole('spinbutton');
@@ -71,7 +73,7 @@ describe('<NumberInput />', () => {
     expect(inputElement).toHaveValue(1);
   });
 
-  it('clamps value to 0 when empty with no min', async () => {
+  it('clamps value to 0 when empty with no min on blur', async () => {
     render(<NumberInput defaultValue="5" />);
 
     const inputElement = screen.getByRole('spinbutton');
@@ -82,6 +84,28 @@ describe('<NumberInput />', () => {
     expect(inputElement).toHaveValue(0);
   });
 
+  it('prevents typing negative sign if min is greater than or equal to 0', async () => {
+    render(<NumberInput defaultValue="5" min={0} />);
+
+    const inputElement = screen.getByRole('spinbutton');
+
+    await userEvent.type(inputElement, '{backspace}');
+    await userEvent.type(inputElement, '-1');
+
+    expect(inputElement).toHaveValue(1);
+  });
+
+  it('allows typing negative sign if min is less than 0', async () => {
+    render(<NumberInput defaultValue="5" min={-5} />);
+
+    const inputElement = screen.getByRole('spinbutton');
+
+    await userEvent.type(inputElement, '{backspace}');
+    await userEvent.type(inputElement, '-1');
+
+    expect(inputElement).toHaveValue(-1);
+  });
+
   it('respects disabled prop', () => {
     render(<NumberInput disabled />);
 
@@ -91,7 +115,7 @@ describe('<NumberInput />', () => {
   });
 
   it('forwards ref', () => {
-    const ref = { current: null } as React.RefObject<HTMLInputElement>;
+    const ref = { current: null } as RefObject<HTMLInputElement>;
 
     render(<NumberInput ref={ref} />);
 
@@ -100,4 +124,15 @@ describe('<NumberInput />', () => {
     expect(ref.current).toBe(inputElement);
     expect(ref.current).toBeInTheDocument();
   });
+
+  it('accepts callback ref', () => {
+    const refSpy = vi.fn();
+
+    render(<NumberInput ref={refSpy} />);
+
+    const inputElement = screen.getByRole('spinbutton');
+
+    expect(refSpy).toHaveBeenCalledOnce();
+    expect(refSpy).toHaveBeenCalledWith(inputElement);
+  });
 });
diff --git a/gbajs3/src/components/shared/number-input.tsx b/gbajs3/src/components/shared/number-input.tsx
index 8ee132c2..64e91bee 100644
--- a/gbajs3/src/components/shared/number-input.tsx
+++ b/gbajs3/src/components/shared/number-input.tsx
@@ -6,7 +6,7 @@ import {
   type IconButtonProps,
   type TextFieldProps
 } from '@mui/material';
-import { forwardRef, type MouseEvent, useRef } from 'react';
+import { forwardRef, useRef, type MouseEvent, type KeyboardEvent } from 'react';
 import { BiSolidUpArrow, BiSolidDownArrow } from 'react-icons/bi';
 
 type NumberInputProps = TextFieldProps & {
@@ -23,12 +23,15 @@ const commonAdornmentButtonProps: IconButtonProps = {
 const preventDefault = (event: MouseEvent<HTMLButtonElement>) =>
   event.preventDefault();
 
+const replaceLeadingZeros = (value: string) => value.replace(/^0+/, '');
+
 export const NumberInput = forwardRef<HTMLInputElement, NumberInputProps>(
   (
     { disabled = false, size, slotProps, step = 1, min, max, sx, ...rest },
     externalRef
   ) => {
     const internalRef = useRef<HTMLInputElement | null>(null);
+    const isIntermediateValue = useRef(false);
 
     const callbackRef = (element: HTMLInputElement | null) => {
       internalRef.current = element;
@@ -54,23 +57,21 @@ export const NumberInput = forwardRef<HTMLInputElement, NumberInputProps>(
     const increment = (e: MouseEvent<HTMLButtonElement>) => {
       preventDefault(e);
 
-      if (!internalRef.current) return;
-
-      const currentValue = internalRef.current.valueAsNumber;
-      const newValue = clamp(currentValue + step);
-
-      dispatchEvent(newValue);
+      if (internalRef.current) {
+        const currentValue = internalRef.current?.valueAsNumber;
+        const newValue = clamp(currentValue + step);
+        dispatchEvent(newValue);
+      }
     };
 
     const decrement = (e: MouseEvent<HTMLButtonElement>) => {
       preventDefault(e);
 
-      if (!internalRef.current) return;
-
-      const currentValue = internalRef.current.valueAsNumber;
-      const newValue = clamp(currentValue - step);
-
-      dispatchEvent(newValue);
+      if (internalRef.current) {
+        const currentValue = internalRef.current?.valueAsNumber;
+        const newValue = clamp(currentValue - step);
+        dispatchEvent(newValue);
+      }
     };
 
     const enforceRange = () => {
@@ -83,6 +84,29 @@ export const NumberInput = forwardRef<HTMLInputElement, NumberInputProps>(
       }
     };
 
+    const sanitizeInput = () => {
+      if (internalRef.current && !isIntermediateValue.current) {
+        const value = internalRef.current.valueAsNumber;
+
+        if (isNaN(value) || value === undefined)
+          internalRef.current.value = '0';
+        else internalRef.current.value = clamp(value).toString();
+      }
+    };
+
+    const handleIntermediateValue = (e: KeyboardEvent<HTMLInputElement>) => {
+      if (e.key === '-') {
+        if (min !== undefined && Number(min) >= 0) {
+          e.preventDefault();
+        } else if (internalRef.current) {
+          internalRef.current.value = replaceLeadingZeros(
+            internalRef.current.value
+          );
+          isIntermediateValue.current = true;
+        }
+      } else isIntermediateValue.current = false;
+    };
+
     return (
       <TextField
         inputRef={callbackRef}
@@ -124,14 +148,8 @@ export const NumberInput = forwardRef<HTMLInputElement, NumberInputProps>(
                 </Stack>
               </InputAdornment>
             ),
-            onInput: () => {
-              if (internalRef.current) {
-                const value = internalRef?.current.valueAsNumber;
-                if (isNaN(value) || value === undefined)
-                  internalRef.current.value = min ? min.toString() : '0';
-                else internalRef.current.value = value.toString();
-              }
-            },
+            onInput: sanitizeInput,
+            onKeyDown: handleIntermediateValue,
             onBlur: enforceRange,
             ...slotProps?.input
           },