diff --git a/src/osx/cocoa/dataview.mm b/src/osx/cocoa/dataview.mm
index d5939b62ec..3b603a36e9 100644
--- a/src/osx/cocoa/dataview.mm
+++ b/src/osx/cocoa/dataview.mm
@@ -2092,7 +2092,7 @@ wxCocoaDataViewControl::wxCocoaDataViewControl(wxWindow* peer,
       ),
       m_DataSource(NULL),
       m_OutlineView([[wxCocoaOutlineView alloc] init]),
-      m_expanderWidth(0)
+      m_expanderWidth(-1)
 {
     // initialize scrollview (the outline view is part of a scrollview):
     NSScrollView* scrollview = (NSScrollView*) GetWXWidget();
@@ -2254,7 +2254,7 @@ void wxCocoaDataViewControl::FitColumnWidthToContent(unsigned int pos)
               m_view(view),
               m_column(columnIndex),
               m_indent(0),
-              m_expander(0),
+              m_expander(-1),
               m_tableColumn(column)
         {
             // account for indentation in the column with expander
@@ -2275,7 +2275,7 @@ void wxCocoaDataViewControl::FitColumnWidthToContent(unsigned int pos)
             if ( m_indent )
                 cellWidth += m_indent * [m_view levelForRow:row];
 
-            if ( m_expander == 0 && m_tableColumn == [m_view outlineTableColumn] )
+            if ( m_expander == -1 && m_tableColumn == [m_view outlineTableColumn] )
             {
                 NSRect rc = [m_view frameOfOutlineCellAtRow:row];
                 m_expander = ceil(rc.origin.x + rc.size.width);
@@ -2366,10 +2366,10 @@ void wxCocoaDataViewControl::FitColumnWidthToContent(unsigned int pos)
 
     // there might not necessarily be an expander in the rows we've examined above so let's
     // globally store the expander width for re-use because it should always be the same
-    if ( m_expanderWidth == 0 )
+    if ( m_expanderWidth == -1 )
         m_expanderWidth = calculator.GetExpanderWidth();
 
-    [column setWidth:calculator.GetMaxWidth() + m_expanderWidth];
+    [column setWidth:calculator.GetMaxWidth() + wxMax(0, m_expanderWidth)];
 }
 
 //