diff --git a/src/pretix/plugins/banktransfer/templatetags/ibanformat.py b/src/pretix/plugins/banktransfer/templatetags/ibanformat.py
index 3ca7100953..8901312e9b 100644
--- a/src/pretix/plugins/banktransfer/templatetags/ibanformat.py
+++ b/src/pretix/plugins/banktransfer/templatetags/ibanformat.py
@@ -5,4 +5,6 @@ register = template.Library()
 
 @register.filter
 def ibanformat(value):
+    if not value:
+        return ''
     return ' '.join(value[i:i + 4] for i in range(0, len(value), 4))