diff --git a/gio/gdbus-2.0/codegen/codegen.py b/gio/gdbus-2.0/codegen/codegen.py
index 3a3af43fe..1789cb33a 100644
--- a/gio/gdbus-2.0/codegen/codegen.py
+++ b/gio/gdbus-2.0/codegen/codegen.py
@@ -1570,7 +1570,9 @@ class CodeGenerator:
         self.c.write('static void %s_proxy_iface_init (%sIface *iface);\n'
                      '\n'%(i.name_lower, i.camel_name))
         self.c.write('G_DEFINE_TYPE_WITH_CODE (%sProxy, %s_proxy, G_TYPE_DBUS_PROXY,\n'%(i.camel_name, i.name_lower))
+        self.c.write('#if GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_38\n')
         self.c.write('                         G_ADD_PRIVATE (%sProxy)\n'%(i.camel_name))
+        self.c.write('#endif\n')
         self.c.write('                         G_IMPLEMENT_INTERFACE (%sTYPE_%s, %s_proxy_iface_init));\n\n'%(i.ns_upper, i.name_upper, i.name_lower))
 
         # finalize
@@ -1795,12 +1797,17 @@ class CodeGenerator:
         self.c.write('static void\n'
                      '%s_proxy_init (%sProxy *proxy)\n'
                      '{\n'
+                     '#if GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_38\n'
                      '  proxy->priv = %s_proxy_get_instance_private (proxy);\n'
+                     '#else\n'
+                     '  proxy->priv = G_TYPE_INSTANCE_GET_PRIVATE (proxy, %sTYPE_%s_PROXY, %sProxyPrivate);\n'
+                     '#endif\n\n'
                      '  g_dbus_proxy_set_interface_info (G_DBUS_PROXY (proxy), %s_interface_info ());\n'
                      '}\n'
                      '\n'
                      %(i.name_lower, i.camel_name,
                        i.name_lower,
+                       i.ns_upper, i.name_upper, i.camel_name,
                        i.name_lower))
         self.c.write('static void\n'
                      '%s_proxy_class_init (%sProxyClass *klass)\n'
@@ -1819,8 +1826,10 @@ class CodeGenerator:
                      '\n'%(i.name_lower, i.camel_name,
                            i.name_lower, i.name_lower, i.name_lower, i.name_lower, i.name_lower))
         if len(i.properties) > 0:
-            self.c.write('\n'
-                         '  %s_override_properties (gobject_class, 1);\n'%(i.name_lower))
+            self.c.write('  %s_override_properties (gobject_class, 1);\n\n'%(i.name_lower))
+        self.c.write('#if GLIB_VERSION_MAX_ALLOWED < GLIB_VERSION_2_38\n'
+                     '  g_type_class_add_private (klass, sizeof (%sProxyPrivate));\n'
+                     '#endif\n'%(i.camel_name))
         self.c.write('}\n'
                      '\n')
 
@@ -2339,7 +2348,9 @@ class CodeGenerator:
                      %(i.name_lower, i.camel_name))
 
         self.c.write('G_DEFINE_TYPE_WITH_CODE (%sSkeleton, %s_skeleton, G_TYPE_DBUS_INTERFACE_SKELETON,\n'%(i.camel_name, i.name_lower))
+        self.c.write('#if GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_38\n')
         self.c.write('                         G_ADD_PRIVATE (%sSkeleton)\n'%(i.camel_name))
+        self.c.write('#endif\n')
         self.c.write('                         G_IMPLEMENT_INTERFACE (%sTYPE_%s, %s_skeleton_iface_init));\n\n'%(i.ns_upper, i.name_upper, i.name_lower))
 
         # finalize
@@ -2533,9 +2544,14 @@ class CodeGenerator:
         self.c.write('static void\n'
                      '%s_skeleton_init (%sSkeleton *skeleton)\n'
                      '{\n'
+                     '#if GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_38\n'
                      '  skeleton->priv = %s_skeleton_get_instance_private (skeleton);\n'
+                     '#else\n'
+                     '  skeleton->priv = G_TYPE_INSTANCE_GET_PRIVATE (skeleton, %sTYPE_%s_SKELETON, %sSkeletonPrivate);\n'
+                     '#endif\n\n'
                      %(i.name_lower, i.camel_name,
-                       i.name_lower))
+                       i.name_lower,
+                       i.ns_upper, i.name_upper, i.camel_name))
         self.c.write('  g_mutex_init (&skeleton->priv->lock);\n')
         self.c.write('  skeleton->priv->context = g_main_context_ref_thread_default ();\n')
         if len(i.properties) > 0:
@@ -2587,6 +2603,12 @@ class CodeGenerator:
         self.c.write('  skeleton_class->get_properties = %s_skeleton_dbus_interface_get_properties;\n'%(i.name_lower))
         self.c.write('  skeleton_class->flush = %s_skeleton_dbus_interface_flush;\n'%(i.name_lower))
         self.c.write('  skeleton_class->get_vtable = %s_skeleton_dbus_interface_get_vtable;\n'%(i.name_lower))
+
+        self.c.write('\n'
+                     '#if GLIB_VERSION_MAX_ALLOWED < GLIB_VERSION_2_38\n'
+                     '  g_type_class_add_private (klass, sizeof (%sSkeletonPrivate));\n'
+                     '#endif\n'%(i.camel_name))
+
         self.c.write('}\n'
                      '\n')
 
@@ -3370,4 +3392,5 @@ class CodeGenerator:
         if self.generate_objmanager:
             self.generate_object()
             self.generate_object_manager_client()
+
         self.generate_outro()
diff --git a/gio/tests/.gitignore b/gio/tests/.gitignore
index 402f76b13..194d5c74a 100644
--- a/gio/tests/.gitignore
+++ b/gio/tests/.gitignore
@@ -67,6 +67,7 @@ gdbus-proxy-well-known-name
 gdbus-serialization
 gdbus-test-codegen
 gdbus-test-codegen-generated*
+gdbus-test-codegen-old
 gdbus-test-fixture
 gdbus-testserver
 gdbus-threading
diff --git a/gio/tests/Makefile.am b/gio/tests/Makefile.am
index e1ef22a64..758ac174e 100644
--- a/gio/tests/Makefile.am
+++ b/gio/tests/Makefile.am
@@ -350,6 +350,7 @@ test_programs += \
 	gdbus-proxy-threads			\
 	gdbus-proxy-well-known-name		\
 	gdbus-test-codegen			\
+	gdbus-test-codegen-old			\
 	gdbus-threading				\
 	gmenumodel				\
 	$(NULL)
@@ -373,9 +374,12 @@ gdbus_proxy_SOURCES                      = $(gdbus_sessionbus_sources) gdbus-pro
 gdbus_proxy_threads_SOURCES              = $(gdbus_sessionbus_sources) gdbus-proxy-threads.c
 gdbus_proxy_well_known_name_SOURCES      = $(gdbus_sessionbus_sources) gdbus-proxy-well-known-name.c
 gdbus_test_codegen_SOURCES               = $(gdbus_sessionbus_sources) gdbus-test-codegen.c
+nodist_gdbus_test_codegen_SOURCES        = gdbus-test-codegen-generated.c gdbus-test-codegen-generated.h
+gdbus_test_codegen_old_SOURCES           = $(gdbus_sessionbus_sources) gdbus-test-codegen.c
+nodist_gdbus_test_codegen_old_SOURCES    = gdbus-test-codegen-generated.c gdbus-test-codegen-generated.h
+gdbus_test_codegen_old_CPPFLAGS          = $(AM_CPPFLAGS) -DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_36 -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_36
 gdbus_threading_SOURCES                  = $(gdbus_sessionbus_sources) gdbus-threading.c
 gmenumodel_SOURCES                       = $(gdbus_sessionbus_sources) gmenumodel.c
-nodist_gdbus_test_codegen_SOURCES        = gdbus-test-codegen-generated.c gdbus-test-codegen-generated.h
 
 gdbus-test-codegen.o: gdbus-test-codegen-generated.h
 gdbus-test-codegen-generated.h gdbus-test-codegen-generated.c: test-codegen.xml Makefile $(top_builddir)/gio/gdbus-2.0/codegen/gdbus-codegen