diff --git a/var/spack/repos/builtin/packages/perl/package.py b/var/spack/repos/builtin/packages/perl/package.py
index cd1acd1695f..fbf788d106a 100644
--- a/var/spack/repos/builtin/packages/perl/package.py
+++ b/var/spack/repos/builtin/packages/perl/package.py
@@ -167,12 +167,14 @@ def setup_dependent_environment(self, spack_env, run_env, dependent_spec):
             if d.package.extends(self.spec):
                 perl_lib_dirs.append(d.prefix.lib.perl5)
                 perl_bin_dirs.append(d.prefix.bin)
-        perl_bin_path = ':'.join(perl_bin_dirs)
-        perl_lib_path = ':'.join(perl_lib_dirs)
-        spack_env.prepend_path('PATH', perl_bin_path)
-        spack_env.prepend_path('PERL5LIB', perl_lib_path)
-        run_env.prepend_path('PATH', perl_bin_path)
-        run_env.prepend_path('PERL5LIB', perl_lib_path)
+        if perl_bin_dirs:
+            perl_bin_path = ':'.join(perl_bin_dirs)
+            spack_env.prepend_path('PATH', perl_bin_path)
+            run_env.prepend_path('PATH', perl_bin_path)
+        if perl_lib_dirs:
+            perl_lib_path = ':'.join(perl_lib_dirs)
+            spack_env.prepend_path('PERL5LIB', perl_lib_path)
+            run_env.prepend_path('PERL5LIB', perl_lib_path)
 
     def setup_dependent_package(self, module, dependent_spec):
         """Called before perl modules' install() methods.