diff --git a/openmc/material.py b/openmc/material.py
index f137ec0cd..1a4b58599 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -438,7 +438,7 @@ class Material(IDManagerMixin):
             params['percent_type'] = percent_type
 
             ## check if nuclide
-            if str.isdigit(component[-1]):
+            if not component.isalpha():
                 self.add_nuclide(component, **params)
             else: # is element
                 kwargs = params
diff --git a/tests/unit_tests/test_material.py b/tests/unit_tests/test_material.py
index 26ccbc9fe..7b8a60629 100644
--- a/tests/unit_tests/test_material.py
+++ b/tests/unit_tests/test_material.py
@@ -32,6 +32,7 @@ def test_add_components():
                   'O16': 1.0,
                   'Zr': 1.0,
                   'O': 1.0,
+                  'Ag110_m1': 1.0,
                   'U': {'percent': 1.0,
                         'enrichment': 4.5},
                   'Li': {'percent': 1.0,