diff --git a/AMBuildScript b/AMBuildScript
index cba9504..f2e6266 100644
--- a/AMBuildScript
+++ b/AMBuildScript
@@ -151,7 +151,7 @@ class MMSConfig(object):
         else:
           sdk_path = ResolveEnvPath(sdk.envvar, sdk.folder)
         if sdk_path is None:
-          if use_all or sdk_name in sdk_list:
+          if (use_all and sdk_name != 'mock') or sdk_name in sdk_list:
             raise Exception('Could not find a valid path for {0}'.format(sdk.envvar))
           not_found.append(sdk_name)
           continue