diff --git a/bot/exceptions.py b/bot/exceptions.py
index 1ad9fae..621dee3 100644
--- a/bot/exceptions.py
+++ b/bot/exceptions.py
@@ -30,3 +30,10 @@ class DatabaseNoVoteException(ContestException):
 
     def __repr__(self) -> str:
         return 'You can\'t remove a vote that never or no longer exists'
+
+
+class SelfVoteException(ContestException):
+    """A user tried to vote on his own submission."""
+
+    def __repr__(self) -> str:
+        return 'You can\'t vote on your own submission. Please choose another post.'
diff --git a/bot/models.py b/bot/models.py
index ef3fbbb..fb3b072 100644
--- a/bot/models.py
+++ b/bot/models.py
@@ -6,10 +6,10 @@ import logging
 from typing import Iterable, List, TYPE_CHECKING, Tuple, Union
 
 import discord
-from sqlalchemy import Boolean, Column, DateTime, Enum, ForeignKey, Integer, Text
+from sqlalchemy import Boolean, Column, DateTime, Enum, ForeignKey, Integer, JSON, Text
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import relationship
-from sqlalchemy_json import MutableJson
+from sqlalchemy_json import NestedMutableList
 
 from bot import constants, exceptions, helpers
 from bot.constants import ReactionMarker
@@ -83,11 +83,19 @@ class Submission(Base):
     id = Column(Integer, primary_key=True)  # Doubles as the ID this Guild has in Discord
     user = Column(Integer)  # The ID of the user who submitted it.
     timestamp = Column(DateTime)  # When the Submission was posted
-    votes: List[int] = Column(MutableJson)  # A list of IDs correlating to users who voted on this submission.
+    votes: List[int] = Column(NestedMutableList.as_mutable(JSON))  # A list of IDs correlating to users who voted on this submission.
 
     period_id = Column(Integer, ForeignKey("period.id"))  # The id of the period this Submission relates to.
     period = relationship("Period", back_populates="submissions")  # The period this submission was made in.
 
+    def __init__(self, **kwds):
+        # Adds default column behavior for Mutable JSON votes column
+        kwds.setdefault("votes", [])
+        super().__init__(**kwds)
+
+    def __repr__(self) -> str:
+        return 'Submission(id={id}, user={user}, period={period_id}, {votes})'.format(**self.__dict__)
+
     @property
     def count(self) -> int:
         """The number of votes cast for this submission."""
@@ -95,7 +103,9 @@ class Submission(Base):
 
     def increment(self, user: int) -> None:
         """Increase the number of votes by one."""
-        if user in self.votes:
+        if user == self.user:
+            raise exceptions.SelfVoteException()
+        elif user in self.votes:
             raise exceptions.DatabaseDoubleVoteException()
         self.votes.append(user)
 
@@ -242,3 +252,6 @@ class Period(Base):
         """
         self.finished_time = datetime.datetime.utcnow()
         self.active = False
+
+    def __repr__(self) -> str:
+        return 'Period(id={id}, guild={guild_id}, {state.name}, active={active})'.format(**self.__dict__)