diff --git a/openmc/data/data.py b/openmc/data/data.py
index b332344241..e813209f0a 100644
--- a/openmc/data/data.py
+++ b/openmc/data/data.py
@@ -358,7 +358,12 @@ def zam(name):
         symbol, A, state = _GND_NAME_RE.match(name).groups()
     except AttributeError:
         raise ValueError("'{}' does not appear to be a nuclide name in GND "
-                         "format.".format(name))
+                         "format".format(name))
+
+    if symbol not in ATOMIC_NUMBER:
+        raise ValueError("'{}' is not a recognized element symbol"
+                         .format(symbol))
+
     metastable = int(state[2:]) if state else 0
     return (ATOMIC_NUMBER[symbol], int(A), metastable)
 
diff --git a/openmc/material.py b/openmc/material.py
index 1700055268..375e1dca1e 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -413,8 +413,6 @@ class Material(IDManagerMixin):
             Z, _, _ = openmc.data.zam(nuclide)
         except ValueError as e:
             warnings.warn(str(e))
-        except KeyError as e:
-            warnings.warn(repr(e))
         else:
             # For actinides, have the material be depletable by default
             if Z >= 89: