diff --git a/lcl/include/customcombobox.inc b/lcl/include/customcombobox.inc
index d21918731b..98f1fd3de7 100644
--- a/lcl/include/customcombobox.inc
+++ b/lcl/include/customcombobox.inc
@@ -42,15 +42,17 @@ begin
     FItems.Free;
   end;
   // and use the interface based list
-  FItems:= NewStrings;
+  FItems := NewStrings;
 
-  TWSCustomComboBoxClass(WidgetSetClass).SetItemIndex(Self, FItemIndex);
+  if FItemIndex <> -1 then
+    TWSCustomComboBoxClass(WidgetSetClass).SetItemIndex(Self, FItemIndex);
   TWSCustomComboBoxClass(WidgetSetClass).SetStyle(Self, FStyle);
   TWSCustomComboBoxClass(WidgetSetClass).SetArrowKeysTraverseList(Self, FArrowKeysTraverseList);
   TWSCustomComboBoxClass(WidgetSetClass).SetReadOnly(Self, FReadOnly);
   TWSCustomComboBoxClass(WidgetSetClass).SetMaxLength(Self, FMaxLength);
 
-  if FSelStart <> FSelLength then begin
+  if FSelStart <> FSelLength then
+  begin
     ASelStart:= FSelStart;
     ASelLength:= FSelLength;
     SelStart:= ASelStart;
@@ -898,10 +900,10 @@ end;
  ------------------------------------------------------------------------------}
 function TCustomComboBox.GetItemIndex : integer;
 begin
-  if not (csDestroying in ComponentState)
-  and not (csDestroyingHandle in ControlState) and HandleAllocated then
+  if not (csDestroying in ComponentState) and
+     not (csDestroyingHandle in ControlState) and HandleAllocated then
     FItemIndex:= TWSCustomComboBoxClass(WidgetSetClass).GetItemIndex(Self);
-  Result:=FItemIndex;
+  Result := FItemIndex;
 end;
 
 {------------------------------------------------------------------------------
diff --git a/lcl/interfaces/win32/win32listsl.inc b/lcl/interfaces/win32/win32listsl.inc
index a5d73a98ea..f736e19ad4 100644
--- a/lcl/interfaces/win32/win32listsl.inc
+++ b/lcl/interfaces/win32/win32listsl.inc
@@ -375,10 +375,14 @@ begin
     // restore text in edit box
     UpdateComboHeight;
     TWin32WSCustomComboBox.SetText(FSender, EditText);
-    lItemIndex := IndexOf(EditText);
+    if EditText = '' then
+     lItemIndex := -1
+    else
+      lItemIndex := IndexOf(EditText);
     if lItemIndex <> -1 then
       TWin32WSCustomComboBox.SetItemIndex(TCustomComboBox(FSender), lItemIndex);
-  end else
+  end
+  else
     inherited Assign(Source);
 end;
 
diff --git a/lcl/interfaces/win32/win32wsstdctrls.pp b/lcl/interfaces/win32/win32wsstdctrls.pp
index a545ec910d..b7edecc466 100644
--- a/lcl/interfaces/win32/win32wsstdctrls.pp
+++ b/lcl/interfaces/win32/win32wsstdctrls.pp
@@ -858,12 +858,6 @@ end;
 class function TWin32WSCustomComboBox.GetItemIndex(const ACustomComboBox: TCustomComboBox): integer;
 begin
   Result := SendMessage(ACustomComboBox.Handle, CB_GETCURSEL, 0, 0);
-  if Result = LB_ERR Then
-  Begin
-    Assert(False, 'Trace:[TWin32WidgetSet.IntSendMessage3] Could not retrieve item index '+
-        'via LM_GETITEMINDEX; try selecting an item first');
-    Result := -1;
-  End;
 end;
 
 class function TWin32WSCustomComboBox.GetMaxLength(const ACustomComboBox: TCustomComboBox): integer;