diff --git a/lemon/elevator.h b/lemon/elevator.h
--- a/lemon/elevator.h
+++ b/lemon/elevator.h
@@ -27,6 +27,7 @@
 ///for labeling items in push-relabel type algorithms.
 ///
 
+#include <lemon/core.h>
 #include <lemon/bits/traits.h>
 
 namespace lemon {