diff --git a/InvenTree/stock/models.py b/InvenTree/stock/models.py
index 12131b5b58..fa343e9a9c 100644
--- a/InvenTree/stock/models.py
+++ b/InvenTree/stock/models.py
@@ -454,11 +454,11 @@ class StockItem(MPTTModel):
         super().clean()
 
         # Strip serial number field
-        if self.serial:
+        if type(self.serial) is str:
             self.serial = self.serial.strip()
 
         # Strip batch code field
-        if self.batch:
+        if type(self.batch) is str:
             self.batch = self.batch.strip()
 
         try: