diff --git a/geometry/graham_scan_functions.h b/geometry/graham_scan_functions.hpp
similarity index 99%
rename from geometry/graham_scan_functions.h
rename to geometry/graham_scan_functions.hpp
index a3523752a..9a92919eb 100644
--- a/geometry/graham_scan_functions.h
+++ b/geometry/graham_scan_functions.hpp
@@ -34,6 +34,7 @@
 * @author [Lajat Manekar](https://github.com/Lazeeez)
 * 
 *******************************************************************************/
+#include <iostream>     /// for IO operations
 #include <stack>        /// for std::stack
 #include <vector>       /// for std::vector
 #include <algorithm>    /// for std::swap