diff --git a/cfgrammar/src/lib/yacc/parser.rs b/cfgrammar/src/lib/yacc/parser.rs
index d91f05736..50322a902 100644
--- a/cfgrammar/src/lib/yacc/parser.rs
+++ b/cfgrammar/src/lib/yacc/parser.rs
@@ -23,6 +23,7 @@ use super::{
 
 /// The various different possible Yacc parser errors.
 #[derive(Debug, PartialEq, Eq, Clone)]
+#[non_exhaustive]
 pub enum YaccGrammarErrorKind {
     IllegalInteger,
     IllegalName,
diff --git a/lrlex/src/lib/mod.rs b/lrlex/src/lib/mod.rs
index 46f75bf2b..ac1b37008 100644
--- a/lrlex/src/lib/mod.rs
+++ b/lrlex/src/lib/mod.rs
@@ -47,6 +47,7 @@ impl Error for LexBuildError {}
 
 /// The various different possible Lex parser errors.
 #[derive(Debug, PartialEq, Eq, Clone)]
+#[non_exhaustive]
 pub enum LexErrorKind {
     PrematureEnd,
     RoutinesNotSupported,