diff --git a/packages/ra-ui-materialui/src/layout/Layout.tsx b/packages/ra-ui-materialui/src/layout/Layout.tsx
index 833685776f1..3cfcf35acb7 100644
--- a/packages/ra-ui-materialui/src/layout/Layout.tsx
+++ b/packages/ra-ui-materialui/src/layout/Layout.tsx
@@ -229,7 +229,7 @@ const Layout = ({
     ...props
 }: LayoutProps): JSX.Element => {
     const themeProp = useRef(themeOverride);
-    const [theme, setTheme] = useState(createMuiTheme(themeOverride));
+    const [theme, setTheme] = useState(() => createMuiTheme(themeOverride));
 
     useEffect(() => {
         if (themeProp.current !== themeOverride) {