diff --git a/urchin/urdf.py b/urchin/urdf.py
index e15b383..80e8a05 100644
--- a/urchin/urdf.py
+++ b/urchin/urdf.py
@@ -1054,10 +1054,13 @@ def _to_xml(self, parent, path):
                 color.attrib["rgba"] = np.array2string(self.color)[1:-1]
                 node.append(color)
 
-        # For non-top-level elements just save the material with a name
         else:
             node = ET.Element("material")
             node.attrib["name"] = self.name
+            if self.color is not None:
+                color = ET.Element("color")
+                color.attrib["rgba"] = np.array2string(self.color)[1:-1]
+                node.append(color)
         return node
 
     def copy(self, prefix="", scale=None):