diff --git a/src/libslic3r/GCode/Thumbnails.cpp b/src/libslic3r/GCode/Thumbnails.cpp
index edafccbea8..6e2b51f764 100644
--- a/src/libslic3r/GCode/Thumbnails.cpp
+++ b/src/libslic3r/GCode/Thumbnails.cpp
@@ -4,6 +4,7 @@
 ///|/
 #include "Thumbnails.hpp"
 #include "../miniz_extension.hpp"
+#include "../format.hpp"
 
 #include <qoi/qoi.h>
 #include <jpeglib.h>
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 23e17e0018..973fd2b397 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -22,6 +22,7 @@
 #include "PrintConfig.hpp"
 #include "Config.hpp"
 #include "I18N.hpp"
+#include "format.hpp"
 
 #include "SLA/SupportTree.hpp"
 #include "GCode/Thumbnails.hpp"