diff --git a/modules/conop/src/processor.cc b/modules/conop/src/processor.cc
index d9fbf418692ebcd7bfc69bd894f6d878de2faf7a..80eec1fb3f01fb6734ed7e6e6fe7fd1b256019c1 100644
--- a/modules/conop/src/processor.cc
+++ b/modules/conop/src/processor.cc
@@ -16,6 +16,7 @@
 // along with this library; if not, write to the Free Software Foundation, Inc.,
 // 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 //------------------------------------------------------------------------------
+#include <limits>
 #include <ost/log.hh>
 #include <ost/mol/xcs_editor.hh>
 #include <ost/mol/bond_handle.hh>