diff --git a/PortMaster/pylibs/harbourmaster/harbour.py b/PortMaster/pylibs/harbourmaster/harbour.py
index 2965a3f..7d58387 100644
--- a/PortMaster/pylibs/harbourmaster/harbour.py
+++ b/PortMaster/pylibs/harbourmaster/harbour.py
@@ -1368,6 +1368,7 @@ def list_ports_names_new(self, filters=[], sort_by='alphabetical', reverse=False
 
             if 'installed' not in filters:
                 tmp_ports.difference_update(self._source_port_attrs.get('installed', set()))
+                tmp_ports.difference_update(self._installed_port_attrs.get('installed', set()))
             else:
                 # sigh...
                 tmp_ports = set()