diff --git a/openfe/setup/ligand_network_planning.py b/openfe/setup/ligand_network_planning.py
index 8835c9735..8cd120314 100644
--- a/openfe/setup/ligand_network_planning.py
+++ b/openfe/setup/ligand_network_planning.py
@@ -313,7 +313,7 @@ def generate_minimal_redundant_network(
 
 def generate_network_from_names(
     ligands: list[SmallMoleculeComponent],
-    mappers: Union[AtomMapper, Iterable[AtomMapper]],
+    mapper: AtomMapper,
     names: list[tuple[str, str]],
 ) -> LigandNetwork:
     """
@@ -344,7 +344,7 @@ def generate_network_from_names(
     """
     nodes = list(ligands)
 
-    network_planner = ExplicitNetworkGenerator(mappers=mappers, scorer=None)
+    network_planner = ExplicitNetworkGenerator(mappers=mapper, scorer=None)
 
     network = network_planner.generate_network_from_names(
         ligands=nodes, names=names
@@ -355,7 +355,7 @@ def generate_network_from_names(
 
 def generate_network_from_indices(
     ligands: list[SmallMoleculeComponent],
-    mappers: Union[AtomMapper, Iterable[AtomMapper]],
+    mapper: AtomMapper,
     indices: list[tuple[int, int]],
 ) -> LigandNetwork:
     """
@@ -383,7 +383,7 @@ def generate_network_from_indices(
     """
     nodes = list(ligands)
 
-    network_planner = ExplicitNetworkGenerator(mappers=mappers, scorer=None)
+    network_planner = ExplicitNetworkGenerator(mappers=mapper, scorer=None)
     network = network_planner.generate_network_from_indices(
         ligands=nodes, indices=indices
     )
@@ -392,7 +392,7 @@ def generate_network_from_indices(
 
 def load_orion_network(
     ligands: list[SmallMoleculeComponent],
-    mappers: Union[AtomMapper, Iterable[AtomMapper]],
+    mapper: AtomMapper,
     network_file: Union[str, Path],
 ) -> LigandNetwork:
     """Load a :class:`.LigandNetwork` from an Orion NES network file.
@@ -431,7 +431,7 @@ def load_orion_network(
 
         names.append((entry[0], entry[2]))
 
-    network_planner = ExplicitNetworkGenerator(mappers=mappers, scorer=None)
+    network_planner = ExplicitNetworkGenerator(mappers=mapper, scorer=None)
     network = network_planner.generate_network_from_names(
         ligands=ligands, names=names
     )
@@ -441,7 +441,7 @@ def load_orion_network(
 
 def load_fepplus_network(
     ligands: list[SmallMoleculeComponent],
-    mappers: Union[AtomMapper, Iterable[AtomMapper]],
+    mapper: AtomMapper,
     network_file: Union[str, Path],
 ) -> LigandNetwork:
     """Load a :class:`.LigandNetwork` from an FEP+ edges network file.
@@ -480,7 +480,7 @@ def load_fepplus_network(
 
         names.append((entry[2], entry[4]))
 
-    network_planner = ExplicitNetworkGenerator(mappers=mappers, scorer=None)
+    network_planner = ExplicitNetworkGenerator(mappers=mapper, scorer=None)
     network = network_planner.generate_network_from_names(
         ligands=ligands, names=names
     )
diff --git a/openfe/tests/setup/test_network_planning.py b/openfe/tests/setup/test_network_planning.py
index feb456359..9992fc0c5 100644
--- a/openfe/tests/setup/test_network_planning.py
+++ b/openfe/tests/setup/test_network_planning.py
@@ -440,7 +440,7 @@ def test_network_from_names(atom_mapping_basic_test_files, lomap_old_mapper):
     network = openfe.setup.ligand_network_planning.generate_network_from_names(
         ligands=ligs,
         names=requested,
-        mappers=lomap_old_mapper,
+        mapper=lomap_old_mapper,
     )
 
     assert len(network.nodes) == len(ligs)
@@ -464,7 +464,7 @@ def test_network_from_names_bad_name(
         _ = openfe.setup.ligand_network_planning.generate_network_from_names(
             ligands=ligs,
             names=requested,
-            mappers=lomap_old_mapper,
+            mapper=lomap_old_mapper,
         )
 
 
@@ -483,7 +483,7 @@ def test_network_from_names_duplicate_name(
         _ = openfe.setup.ligand_network_planning.generate_network_from_names(
             ligands=ligs,
             names=requested,
-            mappers=lomap_old_mapper,
+            mapper=lomap_old_mapper,
         )
 
 
@@ -497,7 +497,7 @@ def test_network_from_indices(
     network = openfe.setup.ligand_network_planning.generate_network_from_indices(
         ligands=ligs,
         indices=requested,
-        mappers=lomap_old_mapper,
+        mapper=lomap_old_mapper,
     )
 
     assert len(network.nodes) == len(ligs)
@@ -522,7 +522,7 @@ def test_network_from_indices_indexerror(
         network = openfe.setup.ligand_network_planning.generate_network_from_indices(
             ligands=ligs,
             indices=requested,
-            mappers=lomap_old_mapper,
+            mapper=lomap_old_mapper,
         )
 
 
@@ -536,7 +536,7 @@ def test_network_from_indices_disconnected_warning(
         _ = openfe.setup.ligand_network_planning.generate_network_from_indices(
             ligands=ligs,
             indices=requested,
-            mappers=lomap_old_mapper,
+            mapper=lomap_old_mapper,
         )
 
 
@@ -553,7 +553,7 @@ def test_network_from_external(file_fixture, loader, request,
 
     network = loader(
         ligands=[l for l in benzene_modifications.values()],
-        mappers=openfe.LomapAtomMapper(),
+        mapper=openfe.LomapAtomMapper(),
         network_file=network_file,
     )
 
@@ -589,7 +589,7 @@ def test_network_from_external_unknown_edge(file_fixture, loader, request,
     with pytest.raises(KeyError, match="Invalid name"):
         network = loader(
             ligands=ligs,
-            mappers=openfe.LomapAtomMapper(),
+            mapper=openfe.LomapAtomMapper(),
             network_file=network_file,
         )
 
@@ -614,7 +614,7 @@ def test_bad_orion_network(benzene_modifications, tmpdir):
         with pytest.raises(KeyError, match="line does not match"):
             network = openfe.setup.ligand_network_planning.load_orion_network(
                 ligands=[l for l in benzene_modifications.values()],
-                mappers=openfe.LomapAtomMapper(),
+                mapper=openfe.LomapAtomMapper(),
                 network_file='bad_orion_net.dat',
             )
 
@@ -637,6 +637,6 @@ def test_bad_edges_network(benzene_modifications, tmpdir):
         with pytest.raises(KeyError, match="line does not match"):
             network = openfe.setup.ligand_network_planning.load_fepplus_network(
                 ligands=[l for l in benzene_modifications.values()],
-                mappers=openfe.LomapAtomMapper(),
+                mapper=openfe.LomapAtomMapper(),
                 network_file='bad_edges.edges',
             )