diff --git a/cashonly/admin.py b/cashonly/admin.py
index 58641e7..d63c961 100644
--- a/cashonly/admin.py
+++ b/cashonly/admin.py
@@ -114,7 +114,7 @@ class SalesLogEntryAdmin(admin.ModelAdmin):
     list_display = ('account', 'timestamp', 'product', 'count', 'unit_price')
     list_filter = ['account', 'timestamp', 'product']
     # Make sales log entries completely read-only
-    readonly_fields = map(lambda f: f.name, SalesLogEntry._meta.fields)
+    readonly_fields = list(map(lambda f: f.name, SalesLogEntry._meta.fields))
 
 
 class TransactionAdmin(admin.ModelAdmin):
diff --git a/cashonly/models.py b/cashonly/models.py
index 9075539..7301fbe 100644
--- a/cashonly/models.py
+++ b/cashonly/models.py
@@ -9,7 +9,7 @@ from django.utils.translation import ugettext_lazy as _
 from django.utils.translation import ugettext_noop
 from django.db import transaction
 import PIL.Image
-import StringIO
+import io
 
 
 class Account(models.Model):
@@ -138,9 +138,10 @@ class Product(models.Model):
 
 @receiver(pre_save, sender=Product)
 def product_post_save_handler(sender, instance, **kwargs):
+    # FIXME
     img = instance.image
     if img:
-        scaledFile = StringIO.StringIO()
+        scaledFile = io.StringIO()
         img.open(mode='r')
         with img:
             scaled = PIL.Image.open(img)