diff --git a/lib/reporter.js b/lib/reporter.js
index 5d27767eb..342162ceb 100644
--- a/lib/reporter.js
+++ b/lib/reporter.js
@@ -10,7 +10,7 @@ var createErrorFormatter = function(basePath, urlRoot) {
   return function(msg, indentation) {
     // remove domain and timestamp from source files
     // and resolve base path / absolute path urls into absolute path
-    msg = msg.replace(URL_REGEXP, function(full, prefix, path) {
+    msg = (msg || '').replace(URL_REGEXP, function(full, prefix, path) {
       if (prefix === 'base') {
         return basePath + path;
       } else if (prefix === 'absolute') {
diff --git a/test/unit/reporter.spec.coffee b/test/unit/reporter.spec.coffee
index 1f5074ee5..fa416f24e 100644
--- a/test/unit/reporter.spec.coffee
+++ b/test/unit/reporter.spec.coffee
@@ -22,6 +22,8 @@ describe 'reporter', ->
     it 'should indent', ->
       expect(formatError 'Something', '\t').to.equal '\tSomething\n'
 
+    it 'should handle empty message', ->
+      expect(formatError null).to.equal '\n'
 
     it 'should remove domain from files', ->
       expect(formatError 'file http://localhost:8080/base/usr/a.js and ' +