diff --git a/specification/dart.sty b/specification/dart.sty
index 32609abc6..086e2420f 100644
--- a/specification/dart.sty
+++ b/specification/dart.sty
@@ -203,7 +203,7 @@
 
 % Mark a compile-time error in the margin.
 \newcommand{\Error}[1]{%
-  \leavevmode\marginpar{\ensuremath{_{\textcolor{red}{^\ominus}}}}{#1}}
+  \leavevmode\marginpar{\ensuremath{\textcolor{red}{\ominus}}}{#1}}
 
 % Mark a dynamic error in the margin.
 \newcommand{\DynamicError}[1]{%