diff --git a/scripts/nix-build.in b/scripts/nix-build.in
index f8cf318ff..9127d90b2 100755
--- a/scripts/nix-build.in
+++ b/scripts/nix-build.in
@@ -276,7 +276,7 @@ foreach my $expr (@exprs) {
     while (<OUTPATHS>) {chomp; push @outPaths, $_;}
     if (!close OUTPATHS) {
         die "nix-store killed by signal " . ($? & 127) . "\n" if ($? & 127);
-        exit $? >> 8 || 1;
+        exit ($? >> 8 || 1);
     }
 
     next if $dryRun;