diff --git a/src/setuptools_dso/dsocmd.py b/src/setuptools_dso/dsocmd.py
index 6cbc782..f8e38cf 100644
--- a/src/setuptools_dso/dsocmd.py
+++ b/src/setuptools_dso/dsocmd.py
@@ -303,6 +303,7 @@ def initialize_options (self):
         self.build_temp = None
         self.inplace = None
         self.force = None
+        self.editable_mode = False
 
     def finalize_options(self):