diff --git a/casadi-bindings-internal.cabal b/casadi-bindings-internal.cabal
--- a/casadi-bindings-internal.cabal
+++ b/casadi-bindings-internal.cabal
@@ -1,5 +1,5 @@
 name:                casadi-bindings-internal
-version:             0.1.2.1
+version:             0.1.3.0
 license:             LGPL-3
 license-file:        LICENSE
 category:            Numerical, Math
diff --git a/cbits/callback.cpp b/cbits/callback.cpp
--- a/cbits/callback.cpp
+++ b/cbits/callback.cpp
@@ -14,7 +14,7 @@
     //todo: use casadi typedefs in functor.hpp
     typedef int (*hs_callback_t)(Function &f);
     typedef void (*hs_custom_evaluate_t)(CustomFunction &f);
-    typedef Function& (*hs_derivative_generator_t)(Function &f, int nfwd, int nadj);
+    typedef Function& (*hs_derivative_generator_t)(Function &f, int nder);
 }
 
 namespace casadi {
@@ -110,7 +110,7 @@
 
         DerivativeGeneratorHaskellInternal(hs_derivative_generator_t hsdg) :
             FunctorHaskellInternal<hs_derivative_generator_t>(hsdg) {}
-        virtual Function call(Function& fcn, int nfwd, int nadj, void* user_data);
+        virtual Function call(Function& fcn, int nder, void* user_data);
         virtual DerivativeGeneratorHaskellInternal* clone() const {
             return new DerivativeGeneratorHaskellInternal(functor_fun_ptr);
         }
@@ -123,11 +123,11 @@
         }
     };
 
-    Function DerivativeGeneratorHaskellInternal::call(Function& fcn, int nfwd, int nadj, void* user_data) {
+    Function DerivativeGeneratorHaskellInternal::call(Function& fcn, int nder, void* user_data) {
         #ifdef DEBUG_WOO
         std::cout << "DerivativeGeneratorHaskellInternal::call()\n";
         #endif
-        Function& f = functor_fun_ptr(fcn, nfwd, nadj);
+        Function& f = functor_fun_ptr(fcn, nder);
         #ifdef DEBUG_WOO
         std::cout << "DerivativeGeneratorHaskellInternal::call() finished\n";
         #endif
diff --git a/src/Casadi/Internal/Callback.hs b/src/Casadi/Internal/Callback.hs
--- a/src/Casadi/Internal/Callback.hs
+++ b/src/Casadi/Internal/Callback.hs
@@ -36,7 +36,7 @@
   :: FunPtr (CasadiCustomEvaluate' customFunction) -> IO (Ptr customEvaluate)
 
 
-type CasadiDerivativeGenerator' function = Ptr function -> CInt -> CInt -> IO (Ptr function)
+type CasadiDerivativeGenerator' function = Ptr function -> CInt -> IO (Ptr function)
 foreign import ccall "wrapper" mkDerivativeGenerator
   :: CasadiDerivativeGenerator' function -> IO (FunPtr (CasadiDerivativeGenerator' function))
 foreign import ccall safe "new_derivative_generator_haskell" c_newDerivativeGeneratorHaskell