diff --git a/README.md b/README.md
index 7184bb5..e2de1a2 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ $ pip install mpegdash
 ## Test
 
 ```bash
-$ python3 -m unittest discover
+$ python -m unittest discover
 ```
 
 * * *
diff --git a/mpegdash/utils.py b/mpegdash/utils.py
index 7a08a91..560017d 100644
--- a/mpegdash/utils.py
+++ b/mpegdash/utils.py
@@ -18,7 +18,7 @@ def parse_child_nodes(xmlnode, tag_name, node_type):
 
     nodes = []
     for elem in elements:
-        if node_type is str:
+        if isinstance(node_type, str):
             node = xmlnode.firstChild.nodeValue
         else:
             node = node_type()