diff --git a/src/slic3r/GUI/GLShader.cpp b/src/slic3r/GUI/GLShader.cpp
index 02c01d104..b87983bd0 100644
--- a/src/slic3r/GUI/GLShader.cpp
+++ b/src/slic3r/GUI/GLShader.cpp
@@ -3,6 +3,7 @@
 
 #include "3DScene.hpp"
 #include "libslic3r/Utils.hpp"
+#include "libslic3r/format.hpp"
 
 #include <boost/nowide/fstream.hpp>
 #include <GL/glew.h>