diff --git a/src/core/elements.py b/src/core/elements.py
index f0c9f8f..fdfed67 100644
--- a/src/core/elements.py
+++ b/src/core/elements.py
@@ -962,7 +962,7 @@ def registerElement(namespaceUri, elementName, elementClass = None, schemaLocati
             descriptionFileUri = libxml2.catalogResolveSystem(descriptionLocation)
             if descriptionFileUri is None:
                 logs.debug("Missing description file '%s'." % descriptionLocation)
-            else:
+            elif descriptionFileUri.startswith("file://"):
                 descriptionAbsolutePath = descriptionFileUri[len("file://"):]
         else:
             assert not descriptionLocation.startswith("/")