diff --git a/lib/cli.js b/lib/cli.js
index 338a23827..d03381d2d 100755
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -168,14 +168,14 @@ cli.processGrammars = function processGrammars(file, lexFile, jsonMode) {
             grammar = ebnfParser.parse(file);
         }
     } catch (e) {
-        throw new Error('Could not parse jison grammar');
+        throw new Error(e.message + '\nCould not parse jison grammar.');
     }
     try {
         if (lexFile) {
             grammar.lex = require('lex-parser').parse(lexFile);
         }
     } catch (e) {
-        throw new Error('Could not parse lex grammar');
+        throw new Error(e.message + '\nCould not parse lex grammar.');
     }
     return grammar;
 };