diff --git a/src/libslic3r/Flow.cpp b/src/libslic3r/Flow.cpp
index 9ac91c51d4..b367be0226 100644
--- a/src/libslic3r/Flow.cpp
+++ b/src/libslic3r/Flow.cpp
@@ -4,6 +4,7 @@
 #include <cmath>
 #include <assert.h>
 
+#include <boost/algorithm/string/predicate.hpp>
 
 // Mark string for localization and translate.
 #define L(s) Slic3r::I18N::translate(s)