diff -r f13799fbcfea -r fcbd6b251d81 cubicweb/utils.py
--- a/cubicweb/utils.py	Mon Jan 23 15:35:19 2017 +0100
+++ b/cubicweb/utils.py	Fri Jan 27 16:26:09 2017 +0100
@@ -534,7 +534,7 @@
         it = sorted(d.items())
     else:
         it = d.items()
-    res = [key + ': ' + js_dumps(val, predictable)
+    res = [js_dumps(key, predictable) + ': ' + js_dumps(val, predictable)
            for key, val in it]
     return '{%s}' % ', '.join(res)