diff --git a/openmc/data/data.py b/openmc/data/data.py
index 8ccc8d2635..2142a5dc90 100644
--- a/openmc/data/data.py
+++ b/openmc/data/data.py
@@ -607,7 +607,7 @@ def zam(name):
 
     """
     try:
-        symbol, A, state = _GNDS_NAME_RE.match(name).groups()
+        symbol, A, state = _GNDS_NAME_RE.fullmatch(name).groups()
     except AttributeError:
         raise ValueError(f"'{name}' does not appear to be a nuclide name in "
                          "GNDS format")
diff --git a/tests/unit_tests/test_data_misc.py b/tests/unit_tests/test_data_misc.py
index 226d848a50..b65c704af8 100644
--- a/tests/unit_tests/test_data_misc.py
+++ b/tests/unit_tests/test_data_misc.py
@@ -131,7 +131,8 @@ def test_zam():
     assert openmc.data.zam('Am242_m10') == (95, 242, 10)
     with pytest.raises(ValueError):
         openmc.data.zam('garbage')
-
+    with pytest.raises(ValueError):
+        openmc.data.zam('Am242-m1')
 
 def test_half_life():
     assert openmc.data.half_life('H2') is None