diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index a0a1b304d6c..36053045468 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -6,10 +6,10 @@ rec {
 
   firefox = common rec {
     pname = "firefox";
-    version = "55.0.2";
+    version = "55.0.3";
     src = fetchurl {
       url = "mirror://mozilla/firefox/releases/${version}/source/firefox-${version}.source.tar.xz";
-      sha512 = "a27722cb5840aac89752fea0880a7e093e84b50dc78a36dc8c4bd493ffda10fa61446007f680bfe65db7a0debe4c21e6f0bf9f0de9876bba067abdda6fed7be4";
+      sha512 = "3cacc87b97871f3a8c5e97c17ef7025079cb5c81f32377d9402cdad45815ac6c4c4762c79187f1e477910161c2377c42d41de62a50b6741d5d7c1cd70e8c6416";
     };
 
     patches = lib.optional stdenv.isi686 (fetchpatch {