diff --git a/pkgs/development/python-modules/marionette-harness/mozlog.nix b/pkgs/development/python-modules/marionette-harness/mozlog.nix
index 5960848ff63b..605a4ae4a381 100644
--- a/pkgs/development/python-modules/marionette-harness/mozlog.nix
+++ b/pkgs/development/python-modules/marionette-harness/mozlog.nix
@@ -9,14 +9,14 @@
 
 buildPythonPackage rec {
   pname = "mozlog";
-  version = "3.4";
+  version = "3.7";
   name = "${pname}-${version}";
 
   disabled = isPy3k;
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "1m4d9i1kzcmkhipfd5czv05f2s84j1byx3cv4y2irjmwq5v6cyiq";
+    sha256 = "414141131c4f5e7242e69a939d2b74f4ed8dbac12bef93eee4e7125cd1a131e9";
   };
 
   propagatedBuildInputs = [ blessings mozfile ];