diff --git a/muck/models/exit.py b/muck/models/exit.py
index 3ad018b..93acc66 100644
--- a/muck/models/exit.py
+++ b/muck/models/exit.py
@@ -1,6 +1,6 @@
-from muck.models.dbref import Dbref
+from muck.models.dbref import Dbref, ObjectType
 
 class Exit(Dbref):
     __mapper_args__ = {
-        "polymorphic_identity": "exit"
+        "polymorphic_identity": ObjectType.EXIT
     }
diff --git a/muck/models/player.py b/muck/models/player.py
index be7694b..94d6f84 100644
--- a/muck/models/player.py
+++ b/muck/models/player.py
@@ -1,6 +1,6 @@
-from muck.models.dbref import Dbref
+from muck.models.dbref import Dbref, ObjectType
 
 class Player(Dbref):
     __mapper_args__ = {
-        "polymorphic_identity": "player"
+        "polymorphic_identity": ObjectType.PLAYER
     }
diff --git a/muck/models/program.py b/muck/models/program.py
index 8854d47..88e9403 100644
--- a/muck/models/program.py
+++ b/muck/models/program.py
@@ -1,6 +1,6 @@
-from muck.models.dbref import Dbref
+from muck.models.dbref import Dbref, ObjectType
 
 class Program(Dbref):
     __mapper_args__ = {
-        "polymorphic_identity": "program"
+        "polymorphic_identity": ObjectType.PROGRAM
     }
diff --git a/muck/models/room.py b/muck/models/room.py
index 19bc508..4de1232 100644
--- a/muck/models/room.py
+++ b/muck/models/room.py
@@ -1,6 +1,6 @@
-from muck.models.dbref import Dbref
+from muck.models.dbref import Dbref, ObjectType
 
 class Room(Dbref):
     __mapper_args__ = {
-        "polymorphic_identity": "room"
+        "polymorphic_identity": ObjectType.ROOM
     }
diff --git a/muck/models/thing.py b/muck/models/thing.py
index 33af801..3f5815a 100644
--- a/muck/models/thing.py
+++ b/muck/models/thing.py
@@ -1,6 +1,6 @@
-from muck.models.dbref import Dbref
+from muck.models.dbref import Dbref, ObjectType
 
 class Thing(Dbref):
     __mapper_args__ = {
-        "polymorphic_identity": "thing"
+        "polymorphic_identity": ObjectType.THING
     }