diff --git a/simgear/scene/util/SGSceneUserData.cxx b/simgear/scene/util/SGSceneUserData.cxx
index 037cd470..7d97c308 100644
--- a/simgear/scene/util/SGSceneUserData.cxx
+++ b/simgear/scene/util/SGSceneUserData.cxx
@@ -61,7 +61,7 @@ SGSceneUserData::getNumPickCallbacks() const
 }
 
 SGPickCallback*
-SGSceneUserData::getPickCallback(unsigned i = 0) const
+SGSceneUserData::getPickCallback(unsigned i) const
 {
   if (_pickCallbacks.size() <= i)
     return 0;
diff --git a/simgear/scene/util/SGSceneUserData.hxx b/simgear/scene/util/SGSceneUserData.hxx
index 42657e55..8234ef48 100644
--- a/simgear/scene/util/SGSceneUserData.hxx
+++ b/simgear/scene/util/SGSceneUserData.hxx
@@ -35,7 +35,7 @@ public:
 
   /// Access to the pick callbacks of a node.
   unsigned getNumPickCallbacks() const;
-  SGPickCallback* getPickCallback(unsigned i = 0) const;
+  SGPickCallback* getPickCallback(unsigned i) const;
   void setPickCallback(SGPickCallback* pickCallback);
   void addPickCallback(SGPickCallback* pickCallback);