diff --git a/core/src/main/java/org/springframework/security/config/FilterChainMapBeanDefinitionDecorator.java b/core/src/main/java/org/springframework/security/config/FilterChainMapBeanDefinitionDecorator.java
index 7df4caa8a4..044967eb1a 100644
--- a/core/src/main/java/org/springframework/security/config/FilterChainMapBeanDefinitionDecorator.java
+++ b/core/src/main/java/org/springframework/security/config/FilterChainMapBeanDefinitionDecorator.java
@@ -60,7 +60,10 @@ class FilterChainMapBeanDefinitionDecorator implements BeanDefinitionDecorator {
             }
         }
 
-        filterChainProxy.getPropertyValues().addPropertyValue("filterChainMap", new ManagedMap(filterChainMap));
+        ManagedMap map = new ManagedMap(filterChainMap.size());
+        map.putAll(filterChainMap);
+
+        filterChainProxy.getPropertyValues().addPropertyValue("filterChainMap", map);
 
         return holder;
     }