diff --git a/pkgs/applications/networking/browsers/firefox/common.nix b/pkgs/applications/networking/browsers/firefox/common.nix
index 2fc15a42a8bf49..1f1831d3c91807 100644
--- a/pkgs/applications/networking/browsers/firefox/common.nix
+++ b/pkgs/applications/networking/browsers/firefox/common.nix
@@ -141,6 +141,14 @@ stdenv.mkDerivation ({
 
   postPatch = ''
     rm -rf obj-x86_64-pc-linux-gnu
+  '' + lib.optionalString (lib.versionAtLeast ffversion "80") ''
+    substituteInPlace dom/system/IOUtils.h \
+      --replace '#include "nspr/prio.h"'          '#include "prio.h"'
+
+    substituteInPlace dom/system/IOUtils.cpp \
+      --replace '#include "nspr/prio.h"'          '#include "prio.h"' \
+      --replace '#include "nspr/private/pprio.h"' '#include "private/pprio.h"' \
+      --replace '#include "nspr/prtypes.h"'       '#include "prtypes.h"'
   '';
 
   nativeBuildInputs =
diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index 62181321cac9f3..a4f423fd8abb87 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -7,10 +7,10 @@ in
 rec {
   firefox = common rec {
     pname = "firefox";
-    ffversion = "79.0";
+    ffversion = "80.0";
     src = fetchurl {
       url = "mirror://mozilla/firefox/releases/${ffversion}/source/firefox-${ffversion}.source.tar.xz";
-      sha512 = "0zgf7wdcz992a4dy1rj0ax0k65an7h9p9iihka3jy4jd7w4g2d0x4mxz5iqn2y26hmgnkvjb921zh28biikahgygqja3z2pcx26ic0r";
+      sha512 = "3rw30gs1wvd6m2sgsp1wm29rrbkxyf3jsdy8i0azfz9w7hqcfwnv76j3cdf18xghh954hpn3q6w1hr7pgab3z9zjxzyfcnh2mbabyvc";
     };
 
     patches = [