--- gnucash-2.6.12/src/optional/gtkmm/gncmm/wrap_init.cpp.orig	2015-12-01 21:54:54.000000000 +0100
+++ gnucash-2.6.12/src/optional/gtkmm/gncmm/wrap_init.cpp	2016-04-09 08:46:19.147136139 +0200
@@ -52,14 +52,14 @@
     GType qof_instance_get_type (void);
 } // extern "C"
 
-//Declarations of the *_Class::wrap_new() methods, instead of including all the private headers:
+//Private headers have to be included. Otherwise one definition rule is violated.
 
-namespace gnc {  class Account_Class { public: static Glib::ObjectBase* wrap_new(GObject*); };  }
-namespace gnc {  class Book_Class { public: static Glib::ObjectBase* wrap_new(GObject*); };  }
-namespace gnc {  class Commodity_Class { public: static Glib::ObjectBase* wrap_new(GObject*); };  }
-namespace gnc {  class GncInstance_Class { public : static Glib::ObjectBase* wrap_new(GObject*); }; }
-namespace gnc {  class Split_Class { public: static Glib::ObjectBase* wrap_new(GObject*); };  }
-namespace gnc {  class Transaction_Class { public: static Glib::ObjectBase* wrap_new(GObject*); };  }
+#include "private/Account_p.hpp" 
+#include "private/Book_p.hpp" 
+#include "private/Commodity_p.hpp" 
+#include "private/GncInstance_p.hpp" 
+#include "private/Split_p.hpp" 
+#include "private/Transaction_p.hpp" 
 
 namespace gnc
 {
--- gnucash-2.6.12/src/optional/gtkmm/gncmm/private/GncInstance_p.hpp.orig	2015-06-29 01:43:24.000000000 +0200
+++ gnucash-2.6.12/src/optional/gtkmm/gncmm/private/GncInstance_p.hpp	2016-04-09 09:42:14.883898423 +0200
@@ -1,7 +1,7 @@
 // -*- c++ -*-
 // Generated by gtkmmproc -- DO NOT MODIFY!
-#ifndef _GNCMM_GNC_COMMODITY_P_H
-#define _GNCMM_GNC_COMMODITY_P_H
+#ifndef _GNCMM_GNC_GNCINSTANCE_P_H
+#define _GNCMM_GNC_GNCINSTANCE_P_H
 
 
 #include <glibmm/private/object_p.h>
--- gnucash-2.6.12/src/optional/gtkmm/test/Makefile.am.orig	2016-01-25 17:33:23.000000000 +0100
+++ gnucash-2.6.12/src/optional/gtkmm/test/Makefile.am	2016-04-09 11:18:22.803435318 +0200
@@ -24,7 +24,7 @@
 	test-gtkmm.cpp \
 	test-book.cpp
 
-test_gtkmm_HEADERS = \
+noinst_HEADERS = \
 	$(top_srcdir)/${MODULEPATH}/gncmm/Book.hpp
 
 #The tests might require more libraries, but try to keep them