diff --git a/cookbook/serializer.py b/cookbook/serializer.py
index 761e5015..3fe76d8a 100644
--- a/cookbook/serializer.py
+++ b/cookbook/serializer.py
@@ -21,6 +21,8 @@ class CustomDecimalField(serializers.Field):
         if type(data) == int or type(data) == float:
             return data
         elif type(data) == str:
+            if data == '':
+                return 0
             try:
                 return float(data.replace(',', ''))
             except ValueError: