diff --git a/diagrams/__init__.py b/diagrams/__init__.py
index 2e41b4e8..8829a012 100644
--- a/diagrams/__init__.py
+++ b/diagrams/__init__.py
@@ -234,7 +234,7 @@ class Cluster:
         self.label = label
         self.name = "cluster_" + self.label
         if not self._icon:
-            self.icon = icon
+            self._icon = icon
         if not self._icon_size:
             self._icon_size = icon_size