diff --git a/Magick++/demo/demo.cpp b/Magick++/demo/demo.cpp
index 59b1a5b..38e8a4d 100644
--- a/Magick++/demo/demo.cpp
+++ b/Magick++/demo/demo.cpp
@@ -442,8 +442,8 @@
cout << " threshold random ..." << endl;
example = model;
example.label( "Random\nThreshold" );
- example.randomThreshold( Geometry((unsigned int) (0.3*QuantumRange),
- (unsigned int) (0.85*QuantumRange)) );
+ example.randomThreshold( Geometry((size_t) (0.3*QuantumRange),
+ (size_t) (0.85*QuantumRange)) );
images.push_back( example );
cout << " unsharp mask ..." << endl;