1 files changed, 1 insertions, 1 deletions
diff --git a/src/lexer.js b/src/lexer.js
index f559816..5e29e42 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -43,7 +43,7 @@ const lex = (expressionString) => {
     })
 
     if (!matched) {
-      return 'error'
+      throw new Error('Syntax error: unrecognized token')
     }
   }