diff --git a/src/final/02.extra-3.js b/src/final/02.extra-3.js
index c95a57af..d017b94b 100644
--- a/src/final/02.extra-3.js
+++ b/src/final/02.extra-3.js
@@ -21,7 +21,9 @@ function useSafeDispatch(dispatch) {
   // interact with the dom may depend on the value being set
   React.useEffect(() => {
     mountedRef.current = true
-    return () => (mountedRef.current = false)
+    return () => {
+      mountedRef.current = false
+    }
   }, [])
 
   return React.useCallback(
diff --git a/src/utils.js b/src/utils.js
index 2ff73970..44d590a4 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -5,7 +5,9 @@ function useSafeDispatch(dispatch) {
 
   React.useLayoutEffect(() => {
     mounted.current = true
-    return () => (mounted.current = false)
+    return () => {
+      mounted.current = false
+    }
   }, [])
 
   return React.useCallback(