diff --git a/ct_optcon/include/ct/optcon/costfunction/costfunction-impl.hpp b/ct_optcon/include/ct/optcon/costfunction/costfun-impl.hpp
similarity index 100%
rename from ct_optcon/include/ct/optcon/costfunction/costfunction-impl.hpp
rename to ct_optcon/include/ct/optcon/costfunction/costfun-impl.hpp
diff --git a/ct_optcon/include/ct/optcon/costfunction/costfunction.hpp b/ct_optcon/include/ct/optcon/costfunction/costfun.hpp
similarity index 100%
rename from ct_optcon/include/ct/optcon/costfunction/costfunction.hpp
rename to ct_optcon/include/ct/optcon/costfunction/costfun.hpp
diff --git a/ct_optcon/include/ct/optcon/optcon-prespec.h b/ct_optcon/include/ct/optcon/optcon-prespec.h
index 499f95d3a..0f3050df3 100644
--- a/ct_optcon/include/ct/optcon/optcon-prespec.h
+++ b/ct_optcon/include/ct/optcon/optcon-prespec.h
@@ -8,8 +8,8 @@ Licensed under Apache2 license (see LICENSE file in main directory)
 
 #include <ct/core/core-prespec.h>
 
-#include "costfunction/costfunction.hpp"
-#include "costfunction/costfunction-impl.hpp"  //temporary solution (todo)
+#include "costfunction/costfun.hpp"
+#include "costfunction/costfun-impl.hpp"  //temporary solution (todo)
 
 #include "filter/filter.h"
 #include "filter/filter-impl.h"  //temporary solution (todo)
diff --git a/ct_optcon/include/ct/optcon/optcon.h b/ct_optcon/include/ct/optcon/optcon.h
index 41b00296a..9ac99adda 100644
--- a/ct_optcon/include/ct/optcon/optcon.h
+++ b/ct_optcon/include/ct/optcon/optcon.h
@@ -8,7 +8,7 @@ Licensed under Apache2 license (see LICENSE file in main directory)
 
 #include <ct/core/core.h>
 
-#include "costfunction/costfunction.hpp"
+#include "costfunction/costfun.hpp"
 
 #include "constraint/constraint.h"
 
@@ -49,7 +49,7 @@ Licensed under Apache2 license (see LICENSE file in main directory)
 #include "filter/filter.h"
 
 // implementations
-#include "costfunction/costfunction-impl.hpp"
+#include "costfunction/costfun-impl.hpp"
 
 #include "constraint/constraint-impl.h"