diff --git a/lib/spack/spack/architecture.py b/lib/spack/spack/architecture.py
index 62e2619d7f..fad6896387 100644
--- a/lib/spack/spack/architecture.py
+++ b/lib/spack/spack/architecture.py
@@ -240,8 +240,8 @@ class OperatingSystem(object):
     """
 
     def __init__(self, name, version):
-        self.name = name
-        self.version = version
+        self.name = name.replace('-', '_')
+        self.version = str(version).replace('-', '_')
 
     def __str__(self):
         return "%s%s" % (self.name, self.version)