diff --git a/polyply/src/meta_molecule.py b/polyply/src/meta_molecule.py
index a9d8184d..57416809 100644
--- a/polyply/src/meta_molecule.py
+++ b/polyply/src/meta_molecule.py
@@ -133,7 +133,7 @@ def add_monomer(self, current, resname, connections):
         that matches may only refer to already existing nodes.
         But connections can be an empty list.
         """
-        self.add_node(current, resname=resname, build=True)
+        self.add_node(current, resname=resname, build=True, backmap=True)
         for edge in connections:
             if self.has_node(edge[0]) and self.has_node(edge[1]):
                 self.add_edge(edge[0], edge[1])