diff --git a/Base/Axis/IAxis.h b/Base/Axis/IAxis.h
index e9651b5bbe145e90700e2b04565c0d512d20e3aa..00321b4e2520cf6e2ebe782ad983934e2faf3c62 100644
--- a/Base/Axis/IAxis.h
+++ b/Base/Axis/IAxis.h
@@ -15,12 +15,11 @@
 #ifndef BORNAGAIN_BASE_AXIS_IAXIS_H
 #define BORNAGAIN_BASE_AXIS_IAXIS_H
 
+#include "Base/Axis/Bin.h"
 #include <string>
 #include <utility>
 #include <vector>
 
-class Bin1D;
-
 //! Abstract base class for one-dimensional axes.
 
 class IAxis {