diff --git a/bin/spack b/bin/spack
index 3544feb10ac42a2e3a15a123c027dee0935f7ea9..9b1276a866639e385b7378b4b08ddae8e5c9ece4 100755
--- a/bin/spack
+++ b/bin/spack
@@ -138,6 +138,9 @@ def main():
         import spack.util.debug as debug
         debug.register_interrupt_handler()
 
+    from spack.yaml_version_check import check_yaml_versions
+    check_yaml_versions()
+
     spack.spack_working_dir = working_dir
     if args.mock:
         from spack.repository import RepoPath
diff --git a/lib/spack/spack/yaml_version_check.py b/lib/spack/spack/yaml_version_check.py
new file mode 100644
index 0000000000000000000000000000000000000000..7e7bae4edf96973116b067b2b1ab34c3e0f35e70
--- /dev/null
+++ b/lib/spack/spack/yaml_version_check.py
@@ -0,0 +1,55 @@
+##############################################################################
+# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+"""Yaml Version Check is a module for ensuring that config file
+formats are compatible with the current version of Spack."""
+import os.path
+import os
+import llnl.util.tty as tty
+import spack.util.spack_yaml as syaml
+import spack.config
+
+
+def check_yaml_versions():
+    check_compiler_yaml_version()
+
+def check_compiler_yaml_version():
+    config_scopes = spack.config.config_scopes
+    for scope in config_scopes.values():
+        file_name = os.path.join(scope.path, 'compilers.yaml')
+        data = None
+        if os.path.isfile(file_name):
+            with open(file_name) as f:
+                data = syaml.load(f)
+
+        if data:
+            compilers = data['compilers'].items()
+            if len(compilers) > 0:
+                if 'operating_system' not in compilers[0][1]:
+                    new_file = os.path.join(scope.path, '_old_compilers.yaml')
+                    tty.warn('%s in out of date compilers format. ' 
+                             'Moved to %s. Spack automatically generate '
+                             'a compilers config file ' 
+                             % (file_name, new_file))
+                    os.rename(file_name, new_file)