diff --git a/simgear/scene/util/StateAttributeFactory.cxx b/simgear/scene/util/StateAttributeFactory.cxx
index 76124da0..25a0a576 100644
--- a/simgear/scene/util/StateAttributeFactory.cxx
+++ b/simgear/scene/util/StateAttributeFactory.cxx
@@ -39,7 +39,7 @@ StateAttributeFactory::StateAttributeFactory()
 {
     _standardAlphaFunc = new AlphaFunc;
     _standardAlphaFunc->setFunction(osg::AlphaFunc::GREATER);
-    _standardAlphaFunc->setReferenceValue(0.01);
+    _standardAlphaFunc->setReferenceValue(0.01f);
     _standardAlphaFunc->setDataVariance(Object::STATIC);
     _smooth = new ShadeModel;
     _smooth->setMode(ShadeModel::SMOOTH);
diff --git a/simgear/structure/SGSharedPtr.hxx b/simgear/structure/SGSharedPtr.hxx
index f321b12d..98b72f22 100644
--- a/simgear/structure/SGSharedPtr.hxx
+++ b/simgear/structure/SGSharedPtr.hxx
@@ -88,7 +88,7 @@ public:
   { return T::count(_ptr); }
 
   bool valid(void) const
-  { return _ptr; }
+  { return _ptr != NULL; }
 
   void clear()
   { put(); }