diff --git a/include/wx/event.h b/include/wx/event.h
index 16f91819d9..8303647c39 100644
--- a/include/wx/event.h
+++ b/include/wx/event.h
@@ -1448,6 +1448,12 @@ private:
  wxEVT_RIGHT_DCLICK
 */
 
+enum wxMouseWheelAxis
+{
+    wxMOUSE_WHEEL_VERTICAL,
+    wxMOUSE_WHEEL_HORIZONTAL
+};
+
 class WXDLLIMPEXP_CORE wxMouseEvent : public wxEvent,
                                       public wxMouseState
 {
@@ -1535,10 +1541,10 @@ public:
     // should occur for each delta.
     int GetWheelDelta() const { return m_wheelDelta; }
 
-    // Gets the axis the wheel operation concerns, 0 being the y axis as on
-    // most mouse wheels, 1 is the x axis for things like MightyMouse scrolls
-    // or horizontal trackpad scrolling
-    int GetWheelAxis() const { return m_wheelAxis; }
+    // Gets the axis the wheel operation concerns; wxMOUSE_WHEEL_VERTICAL
+    // (most common case) or wxMOUSE_WHEEL_HORIZONTAL (for horizontal scrolling
+    // using e.g. a trackpad).
+    wxMouseWheelAxis GetWheelAxis() const { return m_wheelAxis; }
 
     // Returns the configured number of lines (or whatever) to be scrolled per
     // wheel action.  Defaults to one.
@@ -1560,7 +1566,7 @@ public:
 public:
     int           m_clickCount;
 
-    int           m_wheelAxis;
+    wxMouseWheelAxis m_wheelAxis;
     int           m_wheelRotation;
     int           m_wheelDelta;
     int           m_linesPerAction;
diff --git a/interface/wx/event.h b/interface/wx/event.h
index dce4ea1d60..56193eda9f 100644
--- a/interface/wx/event.h
+++ b/interface/wx/event.h
@@ -2187,6 +2187,16 @@ public:
     wxClipboardTextEvent(wxEventType commandType = wxEVT_NULL, int id = 0);
 };
 
+/**
+    Possible axis values for mouse wheel scroll events.
+
+    @since 2.9.4
+ */
+enum wxMouseWheelAxis
+{
+    wxMOUSE_WHEEL_VERTICAL,     ///< Vertical scroll event.
+    wxMOUSE_WHEEL_HORIZONTAL    ///< Horizontal scroll event.
+};
 
 
 /**
@@ -2440,12 +2450,16 @@ public:
     int GetWheelRotation() const;
 
     /**
-        Gets the axis the wheel operation concerns; @c 0 is the Y axis as on
-        most mouse wheels, @c 1 is the X axis.
+        Gets the axis the wheel operation concerns.
 
-        Note that only some models of mouse have horizontal wheel axis.
+        Usually the mouse wheel is used to scroll vertically so @c
+        wxMOUSE_WHEEL_VERTICAL is returned but some mice (and most trackpads)
+        also allow to use the wheel to scroll horizontally in which case
+        @c wxMOUSE_WHEEL_HORIZONTAL is returned.
+
+        Notice that before wxWidgets 2.9.4 this method returned @c int.
     */
-    int GetWheelAxis() const;
+    wxMouseWheelAxis GetWheelAxis() const;
 
     /**
         Returns @true if the event was a mouse button event (not necessarily a button
diff --git a/src/common/event.cpp b/src/common/event.cpp
index ce1e145c79..9896674c61 100644
--- a/src/common/event.cpp
+++ b/src/common/event.cpp
@@ -554,10 +554,10 @@ wxMouseEvent::wxMouseEvent(wxEventType commandType)
 
     m_clickCount = -1;
 
+    m_wheelAxis = wxMOUSE_WHEEL_VERTICAL;
     m_wheelRotation = 0;
     m_wheelDelta = 0;
     m_linesPerAction = 0;
-    m_wheelAxis = 0;
 }
 
 void wxMouseEvent::Assign(const wxMouseEvent& event)
diff --git a/src/osx/carbon/nonownedwnd.cpp b/src/osx/carbon/nonownedwnd.cpp
index dd0e3d774d..7daa2bf9f5 100644
--- a/src/osx/carbon/nonownedwnd.cpp
+++ b/src/osx/carbon/nonownedwnd.cpp
@@ -547,7 +547,7 @@ WXDLLEXPORT void SetupMouseEvent( wxMouseEvent &wxevent , wxMacCarbonEvent &cEve
             wxevent.m_wheelDelta = 1;
             wxevent.m_linesPerAction = 1;
             if ( axis == kEventMouseWheelAxisX )
-                wxevent.m_wheelAxis = 1;
+                wxevent.m_wheelAxis = wxMOUSE_WHEEL_HORIZONTAL;
         }
         break ;
 
diff --git a/src/osx/cocoa/window.mm b/src/osx/cocoa/window.mm
index 39a737650a..d6832303c6 100644
--- a/src/osx/cocoa/window.mm
+++ b/src/osx/cocoa/window.mm
@@ -633,7 +633,7 @@ void wxWidgetCocoaImpl::SetupMouseEvent( wxMouseEvent &wxevent , NSEvent * nsEve
                 
             if ( fabs(deltaX) > fabs(deltaY) )
             {
-                wxevent.m_wheelAxis = 1;
+                wxevent.m_wheelAxis = wxMOUSE_WHEEL_HORIZONTAL;
                 wxevent.m_wheelRotation = (int)deltaX;
             }
             else