diff --git a/src/debugger/gui/CartMDMWidget.cxx b/src/debugger/gui/CartMDMWidget.cxx
index fe8fa94ef..5c9cbbd33 100644
--- a/src/debugger/gui/CartMDMWidget.cxx
+++ b/src/debugger/gui/CartMDMWidget.cxx
@@ -41,7 +41,7 @@ CartridgeMDMWidget::CartridgeMDMWidget(
       ypos = addBaseInformation(size, "Edwin Blink", info.str(), 15) + myLineHeight;
 
   VariantList items;
-  for(uInt32 i = 0x800; i < (0x800 + myCart.bankCount()); ++i)
+  for(uInt32 i = 0x800; i < (0x800u + myCart.bankCount()); ++i)
   {
     info.str("");
     info << dec << (i & 0xFF) << " ($" << Common::Base::HEX4 << i << ")";