diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 1a69ac6..7368184 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -6286,6 +6286,7 @@ namespace pugi
 			return _root->value && (_root->header & impl::xml_memory_page_value_allocated_or_shared_mask) == 0 ? _root->value - doc.buffer : -1;
 
 		default:
+			assert(false && "Invalid node type");
 			return -1;
 		}
 	}