diff --git a/var/spack/repos/builtin/packages/openmpi/package.py b/var/spack/repos/builtin/packages/openmpi/package.py
index 6d3e12d6e5c..ff5c792e48b 100644
--- a/var/spack/repos/builtin/packages/openmpi/package.py
+++ b/var/spack/repos/builtin/packages/openmpi/package.py
@@ -652,7 +652,8 @@ def configure_args(self):
                     spec['slurm'].prefix))
             else:
                 config_args.extend(self.with_or_without('pmi'))
-            config_args += self.with_or_without('pmix', activation_value='prefix')
+            if spec.satisfies('+pmix'):
+                config_args.append('--with-pmix={0}'.format(spec['pmix'].prefix))
             if spec.satisfies('@3.1.3:') or spec.satisfies('@3.0.3'):
                 if '+static' in spec:
                     config_args.append('--enable-static')