diff --git a/include/gepetto/gui/color-map.hh b/include/gepetto/gui/color-map.hh
index 16317899afdac1f3a727eb0ddf6627d8b7759882..9cbed3c79bb2710126d7cb08b816ddc434937d77 100644
--- a/include/gepetto/gui/color-map.hh
+++ b/include/gepetto/gui/color-map.hh
@@ -31,7 +31,7 @@ namespace gepetto {
           return ColorMap::interpolate(mask_, remap (index));
         }
 
-        void getColor (std::size_t index, osgVector4 color) const {
+        void getColor (std::size_t index, osgVector4& color) const {
           QColor c = getColor(index);
           color[0] = (float)c.redF();
           color[1] = (float)c.greenF();