diff --git a/src/common/PNGLibrary.cxx b/src/common/PNGLibrary.cxx
index 78253203a..2f0e49d1c 100644
--- a/src/common/PNGLibrary.cxx
+++ b/src/common/PNGLibrary.cxx
@@ -300,7 +300,7 @@ void PNGLibrary::loadImagetoSurface(FBSurface& surface)
 void PNGLibrary::writeComments(png_structp png_ptr, png_infop info_ptr,
                                const VariantList& comments)
 {
-  uInt32 numComments = comments.size();
+  uInt32 numComments = uInt32(comments.size());
   if(numComments == 0)
     return;
 
diff --git a/src/debugger/DebuggerParser.cxx b/src/debugger/DebuggerParser.cxx
index e68705290..4bd0da6a5 100644
--- a/src/debugger/DebuggerParser.cxx
+++ b/src/debugger/DebuggerParser.cxx
@@ -1275,7 +1275,7 @@ void DebuggerParser::executeRunTo()
   const CartDebug& cartdbg = debugger.cartDebug();
   const CartDebug::DisassemblyList& list = cartdbg.disassembly().list;
 
-  uInt32 count = 0, max_iterations = list.size();
+  uInt32 count = 0, max_iterations = int(list.size());
 
   // Create a progress dialog box to show the progress searching through the
   // disassembly, since this may be a time-consuming operation
diff --git a/src/debugger/gui/CartRamWidget.cxx b/src/debugger/gui/CartRamWidget.cxx
index ad7184d7f..aea2d17a3 100644
--- a/src/debugger/gui/CartRamWidget.cxx
+++ b/src/debugger/gui/CartRamWidget.cxx
@@ -63,7 +63,7 @@ CartRamWidget::CartRamWidget(
   const uInt16 maxlines = 6;
   StringParser bs(desc, (fwidth - kScrollBarWidth) / myFontWidth);
   const StringList& sl = bs.stringList();
-  uInt32 lines = sl.size();
+  uInt32 lines = uInt32(sl.size());
   if(lines < 3) lines = 3;
   if(lines > maxlines) lines = maxlines;
 
diff --git a/src/debugger/gui/RomListWidget.cxx b/src/debugger/gui/RomListWidget.cxx
index c787eb2d4..87917136c 100644
--- a/src/debugger/gui/RomListWidget.cxx
+++ b/src/debugger/gui/RomListWidget.cxx
@@ -225,7 +225,7 @@ void RomListWidget::scrollToCurrent(int item)
     _currentPos = item - _rows + 1;
   }
 
-  int size = myDisasm->list.size();
+  int size = int(myDisasm->list.size());
   if (_currentPos < 0 || _rows > size)
     _currentPos = 0;
   else if (_currentPos + _rows > size)
diff --git a/src/debugger/gui/TogglePixelWidget.cxx b/src/debugger/gui/TogglePixelWidget.cxx
index c92dd2b8d..6bcfd5796 100644
--- a/src/debugger/gui/TogglePixelWidget.cxx
+++ b/src/debugger/gui/TogglePixelWidget.cxx
@@ -92,7 +92,7 @@ void TogglePixelWidget::setIntState(int value, bool swap)
 int TogglePixelWidget::getIntState()
 {
   // Construct int based on current state and swap
-  uInt32 value = 0, size = _stateList.size();
+  uInt32 value = 0, size = int(_stateList.size());
 
   for(uInt32 i = 0; i < size; ++i)
   {
diff --git a/src/emucore/FrameBuffer.cxx b/src/emucore/FrameBuffer.cxx
index c5046333e..6f81f674e 100644
--- a/src/emucore/FrameBuffer.cxx
+++ b/src/emucore/FrameBuffer.cxx
@@ -850,7 +850,7 @@ bool FrameBuffer::VideoModeList::empty() const
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 uInt32 FrameBuffer::VideoModeList::size() const
 {
-  return myModeList.size();
+  return uInt32(myModeList.size());
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/emucore/M6502.cxx b/src/emucore/M6502.cxx
index 55a382c42..333c897c5 100644
--- a/src/emucore/M6502.cxx
+++ b/src/emucore/M6502.cxx
@@ -386,7 +386,7 @@ uInt32 M6502::addCondBreak(Expression* e, const string& name)
 {
   myBreakConds.emplace_back(unique_ptr<Expression>(e));
   myBreakCondNames.push_back(name);
-  return myBreakConds.size() - 1;
+  return uInt32(myBreakConds.size() - 1);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/gui/CheckListWidget.cxx b/src/gui/CheckListWidget.cxx
index f883a3066..b1badcc44 100644
--- a/src/gui/CheckListWidget.cxx
+++ b/src/gui/CheckListWidget.cxx
@@ -86,7 +86,7 @@ void CheckListWidget::drawWidget(bool hilite)
 {
 //cerr << "CheckListWidget::drawWidget\n";
   FBSurface& s = _boss->dialog().surface();
-  int i, pos, len = _list.size();
+  int i, pos, len = int(_list.size());
 
   // Draw a thin frame around the list and to separate columns
   s.hLine(_x, _y, _x + _w - 1, kColor);
diff --git a/src/gui/EditableWidget.cxx b/src/gui/EditableWidget.cxx
index f3b464b17..a0e8f07e3 100644
--- a/src/gui/EditableWidget.cxx
+++ b/src/gui/EditableWidget.cxx
@@ -59,7 +59,7 @@ void EditableWidget::setText(const string& str, bool)
     if(_filter(tolower(c)))
       _editString.push_back(c);
 
-  _caretPos = _editString.size();
+  _caretPos = int(_editString.size());
 
   _editScrollOffset = (_font.getStringWidth(_editString) - (getEditRect().width()));
   if (_editScrollOffset < 0)
@@ -275,7 +275,7 @@ bool EditableWidget::specialKeys(StellaKey key)
       break;
 
     case KBDK_E:
-      setCaretPos(_editString.size());
+      setCaretPos(int(_editString.size()));
       break;
 
     case KBDK_D:
diff --git a/src/gui/Font.cxx b/src/gui/Font.cxx
index 66c47fed1..9fe8ef3cf 100644
--- a/src/gui/Font.cxx
+++ b/src/gui/Font.cxx
@@ -53,7 +53,7 @@ int Font::getStringWidth(const string& str) const
 {
   // If no width table is specified, use the maximum width
   if(!myFontDesc.width)
-    return myFontDesc.maxwidth * str.size();
+    return myFontDesc.maxwidth * int(str.size());
   else
   {
     int space = 0;
diff --git a/src/gui/GameList.hxx b/src/gui/GameList.hxx
index 4b392211c..2bc4c123f 100644
--- a/src/gui/GameList.hxx
+++ b/src/gui/GameList.hxx
@@ -45,7 +45,7 @@ class GameList
     void setMd5(uInt32 i, const string& md5)
       { myArray[i]._md5 = md5; }
 
-    uInt32 size() const { return myArray.size(); }
+    uInt32 size() const { return uInt32(myArray.size()); }
     void clear() { myArray.clear(); }
 
     void appendGame(const string& name, const string& path, const string& md5,
diff --git a/src/gui/InputTextDialog.cxx b/src/gui/InputTextDialog.cxx
index 8eeb279b9..be6e1bf15 100644
--- a/src/gui/InputTextDialog.cxx
+++ b/src/gui/InputTextDialog.cxx
@@ -72,14 +72,14 @@ void InputTextDialog::initialize(const GUI::Font& lfont, const GUI::Font& nfont,
 
   // Calculate real dimensions
   _w = fontWidth * 35;
-  _h = lineHeight * 4 + labels.size() * (lineHeight + 5);
+  _h = lineHeight * 4 + int(labels.size()) * (lineHeight + 5);
 
   // Determine longest label
   for(i = 0; i < labels.size(); ++i)
   {
     if(labels[i].length() > lwidth)
     {
-      lwidth = labels[i].length();
+      lwidth = int(labels[i].length());
       maxIdx = i;
     }
   }
diff --git a/src/gui/ListWidget.cxx b/src/gui/ListWidget.cxx
index 6ec70fca5..7c9263c2c 100644
--- a/src/gui/ListWidget.cxx
+++ b/src/gui/ListWidget.cxx
@@ -147,7 +147,7 @@ const string& ListWidget::getSelectedString() const
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void ListWidget::scrollTo(int item)
 {
-  int size = _list.size();
+  int size = int(_list.size());
   if (item >= size)
     item = size - 1;
   if (item < 0)
@@ -163,7 +163,7 @@ void ListWidget::scrollTo(int item)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void ListWidget::recalc()
 {
-  int size = _list.size();
+  int size = int(_list.size());
 
   if (_currentPos >= size)
     _currentPos = size - 1;
@@ -175,7 +175,7 @@ void ListWidget::recalc()
 
   _editMode = false;
 
-  _scrollBar->_numEntries     = _list.size();
+  _scrollBar->_numEntries     = int(_list.size());
   _scrollBar->_entriesPerPage = _rows;
 
   // Reset to normal data entry
@@ -340,7 +340,7 @@ bool ListWidget::handleEvent(Event::Type e)
 
   bool handled = true;
   int oldSelectedItem = _selectedItem;
-  int size = _list.size();
+  int size = int(_list.size());
 
   switch(e)
   {
diff --git a/src/gui/RomAuditDialog.cxx b/src/gui/RomAuditDialog.cxx
index e231ccc3b..1647ba2dd 100644
--- a/src/gui/RomAuditDialog.cxx
+++ b/src/gui/RomAuditDialog.cxx
@@ -129,7 +129,7 @@ void RomAuditDialog::auditRoms()
   // the ROMs, since this is usually a time-consuming operation
   ProgressDialog progress(this, instance().frameBuffer().font(),
                           "Auditing ROM files ...");
-  progress.setRange(0, files.size() - 1, 5);
+  progress.setRange(0, int(files.size()) - 1, 5);
 
   // Create a entry for the GameList for each file
   Properties props;
diff --git a/src/gui/StringListWidget.cxx b/src/gui/StringListWidget.cxx
index 8a8f5e412..59cb47c2a 100644
--- a/src/gui/StringListWidget.cxx
+++ b/src/gui/StringListWidget.cxx
@@ -48,7 +48,7 @@ void StringListWidget::setList(const StringList& list)
 void StringListWidget::drawWidget(bool hilite)
 {
   FBSurface& s = _boss->dialog().surface();
-  int i, pos, len = _list.size();
+  int i, pos, len = int(_list.size());
 
   // Draw a thin frame around the list.
   s.hLine(_x, _y, _x + _w - 1, kColor);
diff --git a/src/gui/TabWidget.cxx b/src/gui/TabWidget.cxx
index ec728743f..41964461e 100644
--- a/src/gui/TabWidget.cxx
+++ b/src/gui/TabWidget.cxx
@@ -70,7 +70,7 @@ int TabWidget::addTab(const string& title)
 {
   // Add a new tab page
   _tabs.push_back(Tab(title));
-  int numTabs = _tabs.size();
+  int numTabs = int(_tabs.size());
 
   // Determine the new tab width
   int newWidth = _font.getStringWidth(title) + 2 * kTabPadding;
diff --git a/src/gui/Widget.cxx b/src/gui/Widget.cxx
index bde8d0267..866238e89 100644
--- a/src/gui/Widget.cxx
+++ b/src/gui/Widget.cxx
@@ -201,7 +201,7 @@ Widget* Widget::setFocusForChain(GuiObject* boss, WidgetArray& arr,
                                  bool emitFocusEvents)
 {
   FBSurface& s = boss->dialog().surface();
-  int size = arr.size(), pos = -1;
+  int size = int(arr.size()), pos = -1;
   Widget* tmp;
   for(int i = 0; i < size; ++i)
   {