diff --git a/unittests/test_property.py b/unittests/test_property.py
index 8c8ee3a6f83e1660ca53edf5897ff85d1ae1cd20..834b1be582c58c60f70331de9cb0d0d6414fd6c9 100644
--- a/unittests/test_property.py
+++ b/unittests/test_property.py
@@ -92,22 +92,20 @@ def test_selected_reference_list():
     assert isinstance(testrecord.get_property("Conductor").value[0], Entity)
 
 
-PROPS = {
-    10:  db.INTEGER,
-    20:  db.REFERENCE,
-    30:  "SomeRT",
-}
-
-
-def dummy_retrieve(self):
-    self.datatype = PROPS[self.id]
-    self.is_valid = lambda: True
-
-
-Entity.retrieve = dummy_retrieve
-
-
 def test_is_reference():
+    PROPS = {
+        10:  db.INTEGER,
+        20:  db.REFERENCE,
+        30:  "SomeRT",
+    }
+
+    def dummy_retrieve(self):
+        self.datatype = PROPS[self.id]
+        self.is_valid = lambda: True
+    # replace retrieve function by dummy
+    real_retrieve = Entity.retrieve
+    Entity.retrieve = dummy_retrieve
+
     p1 = Property(id=1, datatype=db.INTEGER)
     p2 = Property(id=2, datatype=db.DOUBLE)
     p3 = Property(id=3, datatype=db.TEXT)
@@ -133,3 +131,6 @@ def test_is_reference():
     assert p10.is_reference(server_retrieval=True) is False
     assert p20.is_reference(server_retrieval=True) is True
     assert p30.is_reference(server_retrieval=True) is True
+
+    # restore retrieve function with original
+    Entity.retrieve = real_retrieve