diff --git a/libvips/colour/sRGB2HSV.c b/libvips/colour/sRGB2HSV.c
index f3028dde..46e84de5 100644
--- a/libvips/colour/sRGB2HSV.c
+++ b/libvips/colour/sRGB2HSV.c
@@ -87,7 +87,7 @@ vips_sRGB2HSV_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
 				q[0] = (unsigned char) (((int)(p[0] - p[1]) / delta) + 171);
 			}
 
-			q[1]= (unsigned char)  ((int) delta/c_max);
+			q[1]= (unsigned char)  ((int) delta*256/c_max);
 
 		}