diff --git a/ortools/glop/variable_values.h b/ortools/glop/variable_values.h
index f1311b60d7..d2919002e9 100644
--- a/ortools/glop/variable_values.h
+++ b/ortools/glop/variable_values.h
@@ -14,6 +14,7 @@
 #ifndef OR_TOOLS_GLOP_VARIABLE_VALUES_H_
 #define OR_TOOLS_GLOP_VARIABLE_VALUES_H_
 
+#include <algorithm>
 #include <string>
 #include <vector>