diff --git a/src/tools/vmap4_assembler/TileAssembler.cpp b/src/tools/vmap4_assembler/TileAssembler.cpp
index fea6f038ad2..b3a0af3f008 100644
--- a/src/tools/vmap4_assembler/TileAssembler.cpp
+++ b/src/tools/vmap4_assembler/TileAssembler.cpp
@@ -27,6 +27,7 @@
 #include "VMapDefinitions.h"
 #include <boost/filesystem/directory.hpp>
 #include <boost/filesystem/operations.hpp>
+#include <mutex>
 #include <set>
 
 template<> struct BoundsTrait<VMAP::ModelSpawn*>