diff --git a/src/motif/combobox_native.cpp b/src/motif/combobox_native.cpp
index 80245a8370..fa3204e238 100644
--- a/src/motif/combobox_native.cpp
+++ b/src/motif/combobox_native.cpp
@@ -216,9 +216,9 @@ int wxComboBox::DoAppend(const wxString& item)
 int wxComboBox::DoInsert(const wxString& item, int pos)
 {
     wxCHECK_MSG(!(GetWindowStyle() & wxCB_SORT), -1, wxT("can't insert into sorted list"));
-    wxCHECK_MSG((pos>=0) && (pos<=GetCount()), -1, wxT("invalid index"));
+    wxCHECK_MSG(IsValidInsert(pos), -1, wxT("invalid index"));
 
-    if (pos == GetCount())
+    if ((size_t)pos == GetCount())
         return DoAppend(item);
 
     wxXmString str( item.c_str() );
diff --git a/src/motif/radiobox.cpp b/src/motif/radiobox.cpp
index 0eb64ebb3a..b529840be5 100644
--- a/src/motif/radiobox.cpp
+++ b/src/motif/radiobox.cpp
@@ -198,7 +198,7 @@ void wxRadioBox::SetSelection(int n)
     XmToggleButtonSetState ((Widget) m_radioButtons[n], True, False);
 
     for (size_t i = 0; i < m_noItems; i++)
-        if (i != n)
+        if (i != (size_t)n)
             XmToggleButtonSetState ((Widget) m_radioButtons[i], False, False);
 
     m_inSetValue = false;
@@ -381,11 +381,11 @@ void wxRadioBoxCallback (Widget w, XtPointer clientData,
 
   wxRadioBox *item = (wxRadioBox *) clientData;
   int sel = -1;
-  int i;
+  size_t i;
   const wxWidgetArray& buttons = item->GetRadioButtons();
   for (i = 0; i < item->GetCount(); i++)
     if (((Widget)buttons[i]) == w)
-      sel = i;
+      sel = (int)i;
   item->SetSel(sel);
 
   if (item->InSetValue())