diff --git a/Chapter04/Search.cpp b/Chapter04/Search.cpp
index 56a83598..ce1e6f41 100644
--- a/Chapter04/Search.cpp
+++ b/Chapter04/Search.cpp
@@ -2,6 +2,8 @@
 #include <queue>
 #include <iostream>
 #include <unordered_map>
+#include <algorithm>
+#include <limits>
 
 struct GraphNode
 {