diff --git a/src/moin/converters/moinwiki_in.py b/src/moin/converters/moinwiki_in.py
index 8504b1e88..86f6ee3f0 100644
--- a/src/moin/converters/moinwiki_in.py
+++ b/src/moin/converters/moinwiki_in.py
@@ -80,11 +80,16 @@ class _TableArguments:
 
     def arg_repl(self, args, arg, key=None, value_u=None, value_q1=None, value_q2=None):
         key = self.map_keys.get(key, key)
-        value = (value_u or value_q1 or value_q2).encode("ascii", errors="backslashreplace").decode("unicode-escape")
-        if key:
-            args.keyword[key] = value
-        else:
-            args.positional.append(value)
+        if value_u or value_q1 or value_q2:
+            value = (
+                (value_u or value_q1 or value_q2).encode("ascii", errors="backslashreplace").decode("unicode-escape")
+            )
+            if key:
+                args.keyword[key] = value
+            else:
+                args.positional.append(value)
+        elif key:
+            logging.warning(f"No value supplied for {key} attribute, ignored.")
 
     def number_columns_spanned_repl(self, args, number_columns_spanned):
         args.keyword["number-columns-spanned"] = int(number_columns_spanned)