diff --git a/lib/rules.js b/lib/rules.js
index 06618ab..ad91571 100644
--- a/lib/rules.js
+++ b/lib/rules.js
@@ -259,7 +259,7 @@ var rules = {
       return x.length <= maxLength;
     },
     expectedTypes: ['json', 'ref', 'string'],
-    defaultErrorMessage: function(x, maxLength) { return 'Value was '+(maxLength-x.length)+' character'+((maxLength-x.length !== 1) ? 's' : '')+' longer than the configured maximum length (' + maxLength + ')'; },
+    defaultErrorMessage: function(x, maxLength) { return 'Value was '+(x.length-maxLength)+' character'+((x.length-maxLength !== 1) ? 's' : '')+' longer than the configured maximum length (' + maxLength + ')'; },
     ignoreEmptyString: true,
     checkConfig: function(constraint) {
       if (typeof constraint !== 'number' && parseInt(constraint) !== constraint) {