diff --git a/glue/viewers/common/viewer.py b/glue/viewers/common/viewer.py
index ff289b3a8..efc742a77 100644
--- a/glue/viewers/common/viewer.py
+++ b/glue/viewers/common/viewer.py
@@ -75,6 +75,9 @@ def add_data(self, data):
     def add_subset(self, subset):
         raise NotImplementedError()
 
+    def close(self):
+        raise NotImplementedError()
+
     def __str__(self):
         return self.LABEL