diff --git a/specification/dart.sty b/specification/dart.sty
index 72ec7e296..c7c136d03 100644
--- a/specification/dart.sty
+++ b/specification/dart.sty
@@ -194,11 +194,11 @@
 
 % Mark a compile-time error in the margin.
 \newcommand{\Error}[1]{%
-  \leavevmode\marginpar{\ensuremath{\ominus}}{#1}}
+  \leavevmode\marginpar{\ensuremath{\textcolor{red}{\ominus}}}{#1}}
 
 % Mark a dynamic error in the margin.
 \newcommand{\DynamicError}[1]{%
-  \leavevmode\marginpar{\Lightning}{#1}}
+  \leavevmode\marginpar{\textcolor{red}{\Lightning}}{#1}}
 
 % Used to specify comma separated lists of similar symbols.
 \newcommand{\List}[3]{\ensuremath{{#1}_{#2},\,\ldots,\ {#1}_{#3}}}