diff --git a/src/parser/match_rule.rs b/src/parser/match_rule.rs
index e4f844b..d4221e7 100644
--- a/src/parser/match_rule.rs
+++ b/src/parser/match_rule.rs
@@ -85,6 +85,8 @@ impl<'a> PatternParser<'a> {
         }
     }
 
+    // FIXME: I think this is a missunderstanding of []. It is
+    // supposed to behave like in normal RegExps, i.e. like a set
     fn characters(&mut self) -> Result<Pattern, ParseError> {
         if self.chars.peek() == Some(&'[') {
             self.consume('[')?;