1 files changed, 1 insertions, 0 deletions
diff --git a/lexer.h b/lexer.h
index 7f4cfd0..ff7ab85 100644
--- a/lexer.h
+++ b/lexer.h
@@ -11,6 +11,7 @@ typedef enum TokenType {
 	JUSTIFICATION,
 	PREMISE,
 	ASSUMPTION,
+	NEGATION,
 	CONJUNCTION,
 	DISJUNCTION,
 	IMPLICATION,