diff --git a/inema/wpint.py b/inema/wpint.py
index 2b53683..9e1dc5d 100644
--- a/inema/wpint.py
+++ b/inema/wpint.py
@@ -185,10 +185,20 @@ class WarenpostInt(object):
                            desc=None):
         """Build an 'content item' in the language of the WaPoInt API. Represents one
            line on the customs form."""
+        line_weight_g = int(line_weight_g)
+        if line_weight_g > 2000:
+            raise ValueError('Maximum line weight is 2000g')
+        qty = int(qty)
+        if qty > 99 or qty < 1:
+            raise ValueError('Maximum line quantity is 99')
+        if desc and len(desc) > 33:
+            raise ValueError('Maximum length of contentPieceDescription is 33 chars')
+        if hs_code and (len(hs_code) < 4 or len(hs_code) > 10):
+            raise ValueError('HS-Code must be between 4 and 10 characters long')
         ret = {
             'contentPieceNetweight': line_weight_g,
-            'contentPieceValue': str(int(line_value)),
-            'contentPieceAmount': int(qty),
+            'contentPieceValue': "%.2f" % (line_value),
+            'contentPieceAmount': qty,
             }
         if hs_code:
             ret['contentPieceHsCode'] = str(hs_code)
@@ -201,12 +211,17 @@ class WarenpostInt(object):
     def build_item(self, product, sender, recipient, weight_grams, amount=0, currency='EUR',
                    contents=None):
         """Build an 'item' in the language of the WaPoInt API. Represents one shipment."""
+        weight_grams = int(weight_grams)
+        if weight_grams > 2000:
+            raise ValueError('Maximum item gross weight is 2000g')
+        if len(currency) != 3:
+            raise ValueError('Currency must be expressed as 3-digit ISO-4217 code')
         ret = {
             'product': str(product),
             'serviceLevel': 'STANDARD',
             'shipmentAmount': int(amount),
             'shipmentCurrency': currency,
-            'shipmentGrossWeight': int(weight_grams),
+            'shipmentGrossWeight': weight_grams,
             'shipmentNaturetype': 'SALE_GOODS',
             }
         # merge in the sender and recipient fields