diff --git a/rtengine/color.h b/rtengine/color.h
index 1031ca150..97835ba10 100644
--- a/rtengine/color.h
+++ b/rtengine/color.h
@@ -210,10 +210,12 @@ public:
         return r * workingspace[1][0] + g * workingspace[1][1] + b * workingspace[1][2];
     }
 
+#ifdef __SSE2__
     static vfloat rgbLuminance(vfloat r, vfloat g, vfloat b, const vfloat workingspace[3])
     {
         return r * workingspace[0] + g * workingspace[1] + b * workingspace[2];
     }
+#endif
 
     /**
     * @brief Convert red/green/blue to L*a*b