diff --git a/lib/reporters/json-cov.js b/lib/reporters/json-cov.js
index 7eeab30e2d..73d0009377 100644
--- a/lib/reporters/json-cov.js
+++ b/lib/reporters/json-cov.js
@@ -80,6 +80,10 @@ function map(cov) {
     ret.sloc += data.sloc;
   }
 
+  ret.files.sort(function(a, b) {
+    return a.filename.localeCompare(b.filename);
+  });
+
   if (ret.sloc > 0) {
     ret.coverage = (ret.hits / ret.sloc) * 100;
   }