diff --git a/ipk/src/ar.cpp b/ipk/src/ar.cpp
index 2ea4eed..cebe283 100644
--- a/ipk/src/ar.cpp
+++ b/ipk/src/ar.cpp
@@ -1,5 +1,6 @@
 #include <iostream>
 #include <fstream>
+#include <sstream>
 #include <numeric>
 #include <cmath>
 #include <string>