diff --git a/var/spack/repos/builtin/packages/pythia6/package.py b/var/spack/repos/builtin/packages/pythia6/package.py
index d637b0eb973..32d9ef181df 100644
--- a/var/spack/repos/builtin/packages/pythia6/package.py
+++ b/var/spack/repos/builtin/packages/pythia6/package.py
@@ -153,4 +153,6 @@ def setup_build_environment(self, env):
 
     def cmake_args(self):
         args = ["-DPYTHIA6_VERSION={0}".format(self.version.dotted)]
+        if self.spec.satisfies("platform=darwin"):
+            args.append(self.define("CMAKE_MACOSX_RPATH", True))
         return args