diff --git a/apiserver/apiserver/api/serializers.py b/apiserver/apiserver/api/serializers.py
index 20ece48..a6ddb51 100644
--- a/apiserver/apiserver/api/serializers.py
+++ b/apiserver/apiserver/api/serializers.py
@@ -120,7 +120,7 @@ class TransactionSerializer(serializers.ModelSerializer):
 
         if validated_data['protocoin'] < 0:
             user = validated_data['user']
-            current_protocoin = user.transactions.aggregate(Sum('protocoin'))['protocoin__sum']
+            current_protocoin = user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] or 0
             new_protocoin = current_protocoin + validated_data['protocoin']
             if new_protocoin < 0:
                 raise ValidationError(dict(category='Insufficient funds. Member only has {} protocoin.'.format(current_protocoin)))
@@ -141,7 +141,7 @@ class TransactionSerializer(serializers.ModelSerializer):
         if validated_data['protocoin'] < 0:
             user = validated_data['user']
             # when updating, we need to subtract out the transaction being edited
-            current_protocoin = user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] - instance.protocoin
+            current_protocoin = (user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] or 0) - instance.protocoin
             new_protocoin = current_protocoin + validated_data['protocoin']
             if new_protocoin < 0:
                 raise ValidationError(dict(category='Insufficient funds. Member only had {} protocoin.'.format(current_protocoin)))
diff --git a/apiserver/apiserver/api/views.py b/apiserver/apiserver/api/views.py
index c661646..c722dee 100644
--- a/apiserver/apiserver/api/views.py
+++ b/apiserver/apiserver/api/views.py
@@ -1083,7 +1083,7 @@ class ProtocoinViewSet(Base):
                 destination_member = get_object_or_404(models.Member, id=member_id)
                 destination_user = destination_member.user
 
-                source_user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum']
+                source_user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] or 0
                 source_user_balance = float(source_user_balance)
 
                 if source_user_balance != balance:
@@ -1140,7 +1140,7 @@ class ProtocoinViewSet(Base):
         source_card = get_object_or_404(models.Card, card_number=pk)
         source_user = source_card.user
 
-        user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum']
+        user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] or 0
         user_balance = float(user_balance)
 
         res = dict(
@@ -1183,7 +1183,7 @@ class ProtocoinViewSet(Base):
                     raise exceptions.ValidationError(dict(amount='Amount too small.'))
 
 
-                source_user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum']
+                source_user_balance = source_user.transactions.aggregate(Sum('protocoin'))['protocoin__sum'] or 0
                 source_user_balance = float(source_user_balance)
 
                 if source_user_balance != balance: