diff --git a/src/hdfmap/__init__.py b/src/hdfmap/__init__.py
index 70e63f2..a404d85 100644
--- a/src/hdfmap/__init__.py
+++ b/src/hdfmap/__init__.py
@@ -67,7 +67,7 @@
 ]
 
 __version__ = "1.1.1"
-__date__ = "2025/11/17"
+__date__ = "2025/11/18"
 __author__ = "Dan Porter"
 
 
diff --git a/src/hdfmap/eval_functions.py b/src/hdfmap/eval_functions.py
index c0c7587..21d9a17 100644
--- a/src/hdfmap/eval_functions.py
+++ b/src/hdfmap/eval_functions.py
@@ -322,12 +322,12 @@ def prepare_expression(hdf_file: h5py.File, expression: str, hdf_namespace: dict
         else:
             expression = expression.replace(match.group(), name)
     # find alternate names '(opt1|opt2|opt3)'
-    for alt_names in re_dataset_alternate.findall(expression):  # alt_names = 'opt1|opt2|opt3
+    for alt_names in re_dataset_alternate.findall(expression):  # alt_names = 'opt1|opt2|opt3'
         names = alt_names.split('|')
         # first available name in hdf_namespace or last name
         name = next(
             (n for n in names if n in attributes),
-            next((n for n in names if n in hdf_namespace), names[-1])
+            next((n for n in names if hdf_namespace.get(n, '') in hdf_file), names[-1])
         )
         expression = expression.replace(f"({alt_names})", name)  # replace parentheses
     return expression
diff --git a/tests/test_edge_cases.py b/tests/test_edge_cases.py
index e6a1311..412757f 100644
--- a/tests/test_edge_cases.py
+++ b/tests/test_edge_cases.py
@@ -93,3 +93,19 @@ def test_msmapper_file():
     assert gamma > 1.0, 'unit cell incorrect'
 
 
+@only_dls_file_system
+def test_alternate_name_local_data():
+    f1 = '/dls/science/groups/das/ExampleData/hdfmap_tests/i16/1109527.nxs'
+    f2 = '/dls/science/groups/das/ExampleData/hdfmap_tests/i16/1113658.nxs'
+    m = hdfmap.create_nexus_map(f1)
+
+    with hdfmap.load_hdf(f1) as nxs:
+        scan_command1 = m.get_data(nxs, 'scan_command')
+        print(scan_command1)
+        cmd1 = m.eval(nxs, '(cmd|scan_command)')
+        assert scan_command1 != cmd1, 'cmd and scan_command should not be the same'
+    with hdfmap.load_hdf(f2) as nxs:
+        scan_command2 = m.get_data(nxs, 'scan_command')
+        cmd2 = m.eval(nxs, '(cmd|scan_command)')
+        assert scan_command2 == cmd2, 'cmd and scan_command should be the same'
+    assert cmd1 != cmd2, 'cmd of both files should not be the same'