diff --git a/worker/task.go b/worker/task.go
index 847ba449985..cf2c967a08c 100644
--- a/worker/task.go
+++ b/worker/task.go
@@ -357,6 +357,15 @@ func (qs *queryState) handleValuePostings(ctx context.Context, args funcArgs) er
 		return nil
 	}
 
+	// srcFn.n should be equal to len(q.UidList.Uids) for below implementation(DivideAndRule and
+	// calculate) to work correctly. But we have seen some panics while forming DataKey in
+	// calculate(). panic is of the form "index out of range [4] with length 1". Hence return error
+	// from here when srcFn.n != len(q.UidList.Uids).
+	if srcFn.n != len(q.UidList.Uids) {
+		return errors.Errorf("srcFn.n: %d is not equal to len(q.UidList.Uids): %d, srcFn: %+v in "+
+			"handleValuePostings", srcFn.n, len(q.UidList.GetUids()), srcFn)
+	}
+
 	// This function has small boilerplate as handleUidPostings, around how the code gets
 	// concurrently executed. I didn't see much value in trying to separate it out, because the core
 	// logic constitutes most of the code volume here.