diff --git a/pkgs/build-support/fetchurl/builder.sh b/pkgs/build-support/fetchurl/builder.sh
index b4c8e1f992c..29565d7cdb9 100644
--- a/pkgs/build-support/fetchurl/builder.sh
+++ b/pkgs/build-support/fetchurl/builder.sh
@@ -89,10 +89,6 @@ for url in $urls; do
         if test -z "${!varName}"; then
             echo "warning: unknown mirror:// site \`$site'"
         else
-            # Assume that SourceForge/GNU/kernel mirrors have better
-            # bandwidth than nixos.org.
-            preferHashedMirrors=
-
             mirrors=${!varName}
 
             # Allow command-line override by setting NIX_MIRRORS_$site.