diff --git a/app/models/__init__.py b/app/models/__init__.py
index 76a959a..523d5ac 100644
--- a/app/models/__init__.py
+++ b/app/models/__init__.py
@@ -86,7 +86,7 @@ class AbstractResource(db.Model):  # type: ignore
         :param reason: an opaque string that records the deprecation reason
         :return: if the proxy was deprecated
         """
-        if self.deprecated is not None:
+        if self.deprecated is None:
             logging.info("Deprecating %s (reason=%s)", self.brn, reason)
             self.deprecated = datetime.utcnow()
             self.deprecation_reason = reason