diff --git a/skosprovider_rdf/utils.py b/skosprovider_rdf/utils.py
index de62b52..b874f88 100644
--- a/skosprovider_rdf/utils.py
+++ b/skosprovider_rdf/utils.py
@@ -35,7 +35,7 @@ def rdf_dumper(provider):
         for l in c.labels:
             predicate = URIRef(SKOS + l.type)
             lang = l.language
-            if lang:
+            if isinstance(lang, bytes):
                 lang = lang.decode("UTF-8")
             graph.add((subject, predicate, Literal(l.label, lang=lang)))
         if isinstance(c, Concept):
@@ -55,7 +55,7 @@ def rdf_dumper(provider):
             for n in c.notes:
                 predicate = URIRef(SKOS + "#" + n.type)
                 lang = n.language
-                if lang:
+                if isinstance(lang, bytes):
                     lang = lang.decode("UTF-8")
                 graph.add((subject, predicate, Literal(n.note, lang=lang)))
         elif isinstance(c, Collection):
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 7dad39f..9211271 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -2,6 +2,7 @@
 import os
 from rdflib import Graph
 from rdflib.namespace import RDF, SKOS
+from skosprovider.providers import DictionaryProvider
 from skosprovider_rdf.providers import RDFProvider
 from skosprovider_rdf import utils
 from rdflib.term import URIRef
@@ -17,33 +18,112 @@ def setUp(self):
         # Set up testdata
         self._create_test_data()
 
-        # Set up provider
-        self.provider = RDFProvider(
-            {'id': 'PRODUCTS', 'conceptscheme_id': 1}, self.graph)
-
     def tearDown(self):
-        return
+        del self.larch_dump
+        del self.chestnut_dump
+        del self.world_dump
 
     def _create_test_data(self):
         self.graph = Graph()
-        filepath=os.path.dirname(os.path.realpath(__file__))
-        abspath=os.path.abspath(filepath + "/data/simple_turtle_products")
+        filepath = os.path.dirname(os.path.realpath(__file__))
+        abspath = os.path.abspath(filepath + "/data/simple_turtle_products")
         self.graph.parse(abspath, format="turtle")
 
-        self.u_products=URIRef("http://www.products.com/")
-        self.u_jewellery=URIRef("http://www.products.com/Jewellery")
-        self.u_perfume=URIRef("http://www.products.com/Perfume")
-        self.u_product=URIRef("http://www.products.com/Product")
-        self.u_stuff=URIRef("http://www.products.com/Stuff")
+        self.u_products = URIRef("http://www.products.com/")
+        self.u_jewellery = URIRef("http://www.products.com/Jewellery")
+        self.u_perfume = URIRef("http://www.products.com/Perfume")
+        self.u_product = URIRef("http://www.products.com/Product")
+        self.u_stuff = URIRef("http://www.products.com/Stuff")
+
+        self.larch_dump = {
+            'id': '1',
+            'uri': 'http://id.trees.org/1',
+            'type': 'concept',
+            'labels': [
+                {'type': 'prefLabel', 'language': 'en', 'label': 'The Larch'},
+                {'type': 'prefLabel', 'language': 'nl', 'label': 'De Lariks'}
+            ],
+            'notes': [
+                {'type': 'definition',
+                 'language': 'en',
+                 'note': 'A type of tree.'}
+            ],
+            'narrower': [],
+            'broader': [],
+            'related': [],
+            'member_of': ['3']
+        }
+        self.chestnut_dump = {
+            'id': '2',
+            'uri': 'http://id.trees.org/2',
+            'type': 'concept',
+            'labels': [
+                {'type': 'prefLabel',
+                 'language': 'en',
+                 'label': 'The Chestnut'},
+                {'type': 'altLabel',
+                 'language': 'nl',
+                 'label': 'De Paardekastanje'},
+                {'type': 'altLabel',
+                 'language': 'fr',
+                 'label': 'la châtaigne'}
+            ],
+            'notes': [
+                {
+                    'type': 'definition', 'language': 'en',
+                    'note': 'A different type of tree.'
+                }
+            ],
+            'narrower': [],
+            'broader': [],
+            'related': [],
+            'member_of': ['3']
+        }
+        self.species_dump = {
+            'id': 3,
+            'uri': 'http://id.trees.org/3',
+            'labels': [
+                {'type': 'prefLabel', 'language': 'en', 'label': 'Trees by species'},
+                {'type': 'prefLabel', 'language': 'nl', 'label': 'Bomen per soort'}
+            ],
+            'type': 'collection',
+            'members': ['1', '2'],
+            'member_of': []
+        }
+        self.world_dump = {
+            'id': '1',
+            'uri': 'urn:x-skosprovider:geography:1',
+            'type': 'concept',
+            'labels': [
+                {'type': 'prefLabel', 'language': 'en', 'label': 'World'}
+            ],
+            'notes': [
+            ],
+            'narrower': [2, 3],
+            'broader': [],
+            'related': [],
+            'member_of': []
+        }
+
+        self.tree_provider = DictionaryProvider({'id': 'TREE'}, [self.larch_dump,self.chestnut_dump,self.species_dump])
+        self.world_provider = DictionaryProvider({'id': 'WORLD'}, [self.world_dump])
+        # Set up rdf_provider
+        self.rdf_products_provider = RDFProvider(
+            {'id': 'PRODUCTS', 'conceptscheme_id': 1}, self.graph)
+
+    def test_dump_rdf_to_rdf(self):
+        graph_dump = utils.rdf_dumper(self.rdf_products_provider)
+        xml = graph_dump.serialize(format='xml', encoding="UTF-8").decode()
+        self.assertEquals("<?xml", xml[:5])
 
-        def test_include(self):
-            return
+    def test_dump_rdf_compare_type(self):
+        graph_dump = utils.rdf_dumper(self.rdf_products_provider)
+        self.assertEquals(type(graph_dump), Graph)
 
-    def test_dump_rdf(self):
-        graph_dump=utils.rdf_dumper(self.provider)
-        xml=graph_dump.serialize(format='xml',encoding="UTF-8").decode()
+    def test_dump_tree_to_rdf(self):
+        graph_dump = utils.rdf_dumper(self.tree_provider)
+        xml = graph_dump.serialize(format='xml', encoding="UTF-8").decode()
         self.assertEquals("<?xml", xml[:5])
 
-    def test_compare_dump_rdf(self):
-        graph_dump=utils.rdf_dumper(self.provider)
-        self.assertEquals(type(graph_dump),Graph)
+    def test_include_me(self):
+        return
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