diff --git a/nominatim/api/types.py b/nominatim/api/types.py
index c7e15843..aa3256cd 100644
--- a/nominatim/api/types.py
+++ b/nominatim/api/types.py
@@ -302,7 +302,8 @@ def format_excluded(ids: Any) -> List[int]:
     else:
         raise UsageError("Parameter 'excluded' needs to be a comma-separated list "
                          "or a Python list of numbers.")
-    if not all(isinstance(i, int) or (isinstance(i, str) and i.isdigit()) for i in plist):
+    if not all(isinstance(i, int) or
+               (isinstance(i, str) and (not i or i.isdigit())) for i in plist):
         raise UsageError("Parameter 'excluded' only takes place IDs.")
 
     return [int(id) for id in plist if id]