diff --git a/var/spack/repos/builtin/packages/pythia8/package.py b/var/spack/repos/builtin/packages/pythia8/package.py
index 8660fc8b01d..15effec4004 100644
--- a/var/spack/repos/builtin/packages/pythia8/package.py
+++ b/var/spack/repos/builtin/packages/pythia8/package.py
@@ -68,4 +68,5 @@ def configure_args(self):
         return args
 
     def setup_dependent_run_environment(self, env, dependent_spec):
+        env.set('PYTHIA8', self.prefix)
         env.set('PYTHIA8DATA', self.prefix.share.Pythia8.xmldoc)