diff --git a/src/linkahead/apiutils.py b/src/linkahead/apiutils.py
index 2ad4ef98e3de891bac614cc1f5bbfd83601a34de..d51171c7c59fd0ae8ee202db224f2597f3e9cdae 100644
--- a/src/linkahead/apiutils.py
+++ b/src/linkahead/apiutils.py
@@ -550,7 +550,8 @@ def merge_entities(entity_a: Entity,
             for attribute in ("datatype", "unit", "value"):
                 if (attribute in diff_r2["properties"][key] and
                         diff_r2["properties"][key][attribute] is not None):
-                    if (diff_r1["properties"][key][attribute] is None):
+                    if (attribute not in diff_r1["properties"][key] or
+                            diff_r1["properties"][key][attribute] is None):
                         setattr(entity_a.get_property(key), attribute,
                                 diff_r2["properties"][key][attribute])
                     elif force: