diff --git a/include/mapnik/color.hpp b/include/mapnik/color.hpp
index de35941cf..270caf425 100644
--- a/include/mapnik/color.hpp
+++ b/include/mapnik/color.hpp
@@ -134,9 +134,9 @@ public:
     inline unsigned rgba() const
     {
 #ifdef MAPNIK_BIG_ENDIAN
-        return (alpha_) | (blue_ << 8) | (green_ << 16) | (red_ << 24) ;
+        return static_cast<unsigned>((alpha_) | (blue_ << 8) | (green_ << 16) | (red_ << 24)) ;
 #else
-        return (alpha_ << 24) | (blue_ << 16) | (green_ << 8) | (red_) ;
+        return static_cast<unsigned>((alpha_ << 24) | (blue_ << 16) | (green_ << 8) | (red_)) ;
 #endif
     }
 };