diff --git a/lib/Subtitle/BASE.pm b/lib/Subtitle/BASE.pm
index fc93852..ca129b4 100644
--- a/lib/Subtitle/BASE.pm
+++ b/lib/Subtitle/BASE.pm
@@ -73,4 +73,7 @@ sub events {
   return wantarray ? @{ $self->{events} } : $self->{events};
 }
 
+sub parse { return "Unimplemented by subclass"; }
+sub build { return "Unimplemented by subclass"; }
+
 1;