diff --git a/include/wx/osx/core/colour.h b/include/wx/osx/core/colour.h
index cdb0f83a2c..f5357bcb70 100644
--- a/include/wx/osx/core/colour.h
+++ b/include/wx/osx/core/colour.h
@@ -60,7 +60,7 @@ public:
 #endif
 #if wxOSX_USE_COCOA
     wxColour(WX_NSColor color);
-    WX_NSColor OSXGetNSColor();
+    WX_NSColor OSXGetNSColor() const;
 #endif
     wxColour& operator=(CGColorRef col);
     wxColour& operator=(const wxColour& col);
diff --git a/src/osx/cocoa/colour.mm b/src/osx/cocoa/colour.mm
index a59b71b2c0..331022932f 100644
--- a/src/osx/cocoa/colour.mm
+++ b/src/osx/cocoa/colour.mm
@@ -40,7 +40,7 @@ wxColour::wxColour(WX_NSColor col)
     InitFromComponents(components, noComp);
 }
 
-WX_NSColor wxColour::OSXGetNSColor()
+WX_NSColor wxColour::OSXGetNSColor() const
 {
     return [NSColor colorWithDeviceRed:m_red / 255.0 green:m_green / 255.0 blue:m_blue / 255.0 alpha:m_alpha / 255.0];
 }