diff --git a/src/net/sf/freecol/client/gui/panel/colopedia/FatherDetailPanel.java b/src/net/sf/freecol/client/gui/panel/colopedia/FatherDetailPanel.java
index 0d9a97db4b..683b5c8ebe 100644
--- a/src/net/sf/freecol/client/gui/panel/colopedia/FatherDetailPanel.java
+++ b/src/net/sf/freecol/client/gui/panel/colopedia/FatherDetailPanel.java
@@ -107,7 +107,8 @@ public void addSubTrees(DefaultMutableTreeNode root) {
     @Override
     public void buildDetail(String id, JPanel panel) {
         FoundingFather father = getSpecification().getFoundingFather(id);
-        buildDetail(father, panel);
+        if(father!=null)
+            buildDetail(father, panel);
     }
 
     /**