diff -up ./native/callback.c.ffi ./native/callback.c
--- ./native/callback.c.ffi	2013-07-15 14:41:13.643452439 +0200
+++ ./native/callback.c	2013-07-15 14:47:23.254830318 +0200
@@ -253,7 +253,7 @@ create_callback(JNIEnv* env, jobject obj
     case 'D': cb->fptr_offset = OFFSETOF(env, CallDoubleMethod); break;
     default: cb->fptr_offset = OFFSETOF(env, CallObjectMethod); break;
     }
-    status = ffi_prep_cif_var(&cb->java_cif, java_abi, 2, argc+3, java_ffi_rtype, cb->java_arg_types);
+    status = ffi_prep_cif(&cb->java_cif, java_abi, argc+3, java_ffi_rtype, cb->java_arg_types);
     if (!ffi_error(env, "callback setup (2)", status)) {
       ffi_prep_closure_loc(cb->closure, &cb->cif, callback_dispatch, cb,
                            cb->x_closure);