diff --git a/Essentials/src/main/java/com/earth2me/essentials/config/serializers/MaterialTypeSerializer.java b/Essentials/src/main/java/com/earth2me/essentials/config/serializers/MaterialTypeSerializer.java
index 50e23157293..3fb5c1a5c12 100644
--- a/Essentials/src/main/java/com/earth2me/essentials/config/serializers/MaterialTypeSerializer.java
+++ b/Essentials/src/main/java/com/earth2me/essentials/config/serializers/MaterialTypeSerializer.java
@@ -17,7 +17,9 @@ public Material deserialize(Type type, Object obj) throws SerializationException
         if (obj instanceof String) {
             return Material.matchMaterial((String) obj);
         }
-        return null;
+
+        // Configurate will use an EnumSet to deserialize, which doesn't support null types. Default to air.
+        return Material.AIR;
     }
 
     @Override