diff --git a/scripts/nix-build.in b/scripts/nix-build.in
index bb61e1c..d58d687 100755
--- a/scripts/nix-build.in
+++ b/scripts/nix-build.in
@@ -276,6 +276,7 @@ foreach my $expr (@exprs) {
             }
             # NixOS hack: prevent /etc/bashrc from sourcing /etc/profile.
             $ENV{'__ETC_PROFILE_SOURCED'} = 1;
+            $ENV{'SKIP_CC_CVMFS'} = 1;
         }
         $ENV{'NIX_BUILD_TOP'} = $ENV{'TMPDIR'} = $ENV{'TEMPDIR'} = $ENV{'TMP'} = $ENV{'TEMP'} = $tmp;
         $ENV{'NIX_STORE'} = $Nix::Config::storeDir;