diff --git a/src/pathfinder/npf/npf.cpp b/src/pathfinder/npf/npf.cpp
--- a/src/pathfinder/npf/npf.cpp
+++ b/src/pathfinder/npf/npf.cpp
@@ -8,6 +8,7 @@
 /** @file npf.cpp Implementation of the NPF pathfinder. */
 
 #include "../../stdafx.h"
+#include "../../debug.h"
 #include "../../network/network.h"
 #include "../../viewport_func.h"
 #include "../../ship.h"