ThemeProvider combining styled-components and material-ui in typescript

ThemeProvider.tsx

import * as React from 'react';
import {ThemeProvider as StyledThemeProvider} from 'styled-components';
import {MuiThemeProvider} from '@material-ui/core/styles';
import {StylesProvider} from '@material-ui/styles';
import CssBaseline from '@material-ui/core/CssBaseline';
import {theme, muiTheme} from './';

interface ThemeProviderProps {
  children: React.ReactNode
};

const ThemeProvider = ({ children }: ThemeProviderProps) => {
  const nextTheme = {...theme, ...muiTheme};

  return (
    <StylesProvider injectFirst={true}>
      <CssBaseline />
      <StyledThemeProvider theme={nextTheme}>
        <MuiThemeProvider theme={nextTheme}>{children}</MuiThemeProvider>
      </StyledThemeProvider>
    </StylesProvider>
  )
}

export default ThemeProvider;