diff --git a/src/index/use-swr.ts b/src/index/use-swr.ts
index 02c09e41a..02f253b0a 100644
--- a/src/index/use-swr.ts
+++ b/src/index/use-swr.ts
@@ -278,7 +278,10 @@ export const useSWRHandler = <Data = any, Error = any>(
 
   const returnedData = keepPreviousData
     ? isUndefined(cachedData)
-      ? laggyDataRef.current ?? data
+      // checking undefined to avoid null being fallback as well
+      ? isUndefined(laggyDataRef.current)
+        ? data
+        : laggyDataRef.current
       : cachedData
     : data