diff --git a/pkgs/build-support/fetchurl/mirrors.nix b/pkgs/build-support/fetchurl/mirrors.nix
index 767444e7698..c5107781c33 100644
--- a/pkgs/build-support/fetchurl/mirrors.nix
+++ b/pkgs/build-support/fetchurl/mirrors.nix
@@ -333,4 +333,10 @@ rec {
     ftp://ftp.halifax.rwth-aachen.de/pub/OpenBSD/
     ftp://mirror.switch.ch/pub/OpenBSD/
   ];
+
+  # Steam Runtime mirrors
+  steamrt = [
+    http://repo.steampowered.com/steamrt/
+    https://abbradar.net/steamrt/
+  ];
 }
diff --git a/pkgs/games/steam/update-runtime.py b/pkgs/games/steam/update-runtime.py
index 32442970849..0292e725cea 100755
--- a/pkgs/games/steam/update-runtime.py
+++ b/pkgs/games/steam/update-runtime.py
@@ -40,9 +40,9 @@ def download_file(file_base, file_name, file_url):
 	out.write("    rec {\n")
 	out.write("      name = \"%s\";\n" % file_name)
 	out.write("      md5 = \"%s\";\n" % md5.strip())
+	out.write("      url = \"%s\";\n" % file_url.replace(REPO, "mirror://steamrt", 1))
 	out.write("      source = fetchurl {\n")
-	out.write("        url = \"%s\";\n" % file_url)
-	out.write("        inherit md5;\n")
+	out.write("        inherit url md5;\n")
 	out.write("        name = \"%s\";\n" % file_shortname)
 	out.write("      };\n")
 	out.write("    }\n")