diff --git a/pkgs/applications/misc/rxvt_unicode/wrapper.nix b/pkgs/applications/misc/rxvt_unicode/wrapper.nix
index a7b25e112a97..fd0860b3aaef 100644
--- a/pkgs/applications/misc/rxvt_unicode/wrapper.nix
+++ b/pkgs/applications/misc/rxvt_unicode/wrapper.nix
@@ -12,10 +12,10 @@ in symlinkJoin {
 
   postBuild = ''
     wrapProgram $out/bin/urxvt \
-      --set PERL5LIB : "${perlPackages.makePerlPath perlDeps}" \
+      --prefix PERL5LIB : "${perlPackages.makePerlPath perlDeps}" \
       --suffix-each URXVT_PERL_LIB ':' "$out/lib/urxvt/perl"
     wrapProgram $out/bin/urxvtd \
-      --set PERL5LIB : "${perlPackages.makePerlPath perlDeps}" \
+      --prefix PERL5LIB : "${perlPackages.makePerlPath perlDeps}" \
       --suffix-each URXVT_PERL_LIB ':' "$out/lib/urxvt/perl"
   '';