diff --git a/var/spack/repos/builtin/packages/pmix/package.py b/var/spack/repos/builtin/packages/pmix/package.py
index fb4e37e572b1bc4e657230a934d3fbb96625f69d..2cb5126b535c58c370488d7fc174923f3201c4c8 100644
--- a/var/spack/repos/builtin/packages/pmix/package.py
+++ b/var/spack/repos/builtin/packages/pmix/package.py
@@ -50,6 +50,10 @@ class Pmix(AutotoolsPackage):
     depends_on('libevent@2.0.20:2.0.22,2.1.8')
     depends_on('hwloc@1.11.0:1.11.99,2.0.1:', when='@3.0.0:')
 
+    variant('pmi_backwards_compatibility',
+            default=True,
+            description="Toggle pmi backwards compatibility")
+
     def configure_args(self):
 
         spec = self.spec
@@ -58,6 +62,11 @@ def configure_args(self):
             '--enable-static'
         ]
 
+        if '+pmi_backwards_compatibility' in self.spec:
+            config_args.append('--enable-pmi-backward-compatibility')
+        else:
+            config_args.append('--disable-pmi-backward-compatibility')
+
         # libevent support
         config_args.append(
             '--with-libevent={0}'.format(spec['libevent'].prefix))