diff --git a/newnotation.sty b/newnotation.sty
index 397138f..88d53b9 100755
--- a/newnotation.sty
+++ b/newnotation.sty
@@ -623,7 +623,7 @@
 %   8. optional:  description of arguments for table of notation
 \DeclareDocumentCommand{\renewnotation}{s o m O{0} o m O{} O{}}{%
 	% Check whether macro is not defined so far:
-	\ifundef{#2}%
+	\ifundef{#3}%
 		{\PackageError{newnotation}{renewnotation: Command '\string#2' not defined.}%
 		{Misspelled name?}}{}%
 	%