diff --git a/invoice.fodt b/invoice.fodt
index 9f98a12cc9..76450f2adc 100644
--- a/invoice.fodt
+++ b/invoice.fodt
@@ -706,7 +706,7 @@
       <text:p text:style-name="Table_20_Contents"><text:placeholder text:placeholder-type="text">&lt;/if&gt;</text:placeholder></text:p>
      </table:table-cell>
      <table:table-cell table:style-name="Table1.D5" office:value-type="string">
-      <text:p text:style-name="P10"><text:placeholder text:placeholder-type="text">&lt;(format_number(line.quantity, invoice.party.lang, digits=line.unit.digits if line.unit else None) + (line.unit and (&apos; &apos; + line.unit.symbol) or &apos;&apos;)) or &apos;&apos;&gt;</text:placeholder></text:p>
+      <text:p text:style-name="P10"><text:placeholder text:placeholder-type="text">&lt;format_number_symbol(line.quantity, invoice.party.lang, line.unit, digits=line.unit.digits) if line.unit else format_number(line.quantity, invoice.party.lang)&gt;</text:placeholder></text:p>
      </table:table-cell>
      <table:table-cell table:style-name="Table1.D5" office:value-type="string">
       <text:p text:style-name="P11"><text:placeholder text:placeholder-type="text">&lt;format_currency(line.unit_price, invoice.party.lang, invoice.currency, digits=line.__class__.unit_price.digits[1])&gt;</text:placeholder></text:p>
diff --git a/invoice.py b/invoice.py
index c3d92831a9..4d3f453213 100644
--- a/invoice.py
+++ b/invoice.py
@@ -2302,9 +2302,9 @@ class InvoiceLine(sequence_ordered(), ModelSQL, ModelView, TaxableMixin):
         Lang = pool.get('ir.lang')
         if self.product:
             lang = Lang.get()
-            prefix = (lang.format(
-                    '%.*f', (self.unit.digits, self.quantity or 0))
-                + '%s %s' % (self.unit.symbol, self.product.rec_name))
+            prefix = (lang.format_number_symbol(
+                self.quantity or 0, self.unit, digits=self.unit.digits)
+                + ' %s' % self.product.rec_name)
         elif self.account:
             prefix = self.account.rec_name
         else: