diff --git a/libs/gtkmm2ext/colors.cc b/libs/gtkmm2ext/colors.cc
index b2534b60be..562c570b9a 100644
--- a/libs/gtkmm2ext/colors.cc
+++ b/libs/gtkmm2ext/colors.cc
@@ -240,6 +240,10 @@ HSV::HSV (double hh, double ss, double vv, double aa)
 		/* normalize negative hue values into positive range */
 		h = 360.0 + h;
 	}
+
+	s = max (0.0, min (1.0, s));
+	v = max (0.0, min (1.0, v));
+	a = max (0.0, min (1.0, a));
 }
 
 HSV::HSV (Color c)
@@ -328,6 +332,25 @@ HSV::operator== (const HSV& other)
 		a == other.a;
 }
 
+HSV
+HSV::darker (double factor) const
+{
+	HSV hsv (*this);
+	/* factor == 1.0: reduce all the way to zero */
+	hsv.v -= max (0.0, min (1.0, factor)) * hsv.v;
+	return hsv;
+}
+
+HSV
+HSV::lighter (double factor) const
+{
+	HSV hsv (*this);
+	/* factor == 1.0: increase all the way to 1.0 */
+	hsv.v += max (0.0, min (1.0, factor)) * (1.0 - hsv.v);
+	return hsv;
+}
+
+
 HSV
 HSV::shade (double factor) const
 {
@@ -344,15 +367,21 @@ HSV::shade (double factor) const
 	*/
 
 	if (factor > 1.0) {
-		if (s < 88) {
-			hsv.v += (hsv.v * (factor * 10.0));
-		}
+		/* darker */
+		/* increase saturation (factor is > 1.0, so s grows) */
 		hsv.s *= factor;
+		if (hsv.s >= 0.88) {
+			/* above saturation threshold, so decrease v a bit */
+			hsv.v -= (hsv.v * 0.05);
+		}
 	} else {
-		if (s < 88) {
-			hsv.v -= (hsv.v * (factor * 10.0));
-		}
+		/* lighter */
+		/* reduce saturation, (factor is < 1.0, so s shrinks) */
 		hsv.s *= factor;
+		if (hsv.s > 0.88) {
+			/* still above 88% saturation, so increase v a bit */
+			hsv.v += (hsv.v * 0.05);
+		}
 	}
 
 	hsv.clamp();
diff --git a/libs/gtkmm2ext/gtkmm2ext/colors.h b/libs/gtkmm2ext/gtkmm2ext/colors.h
index 56707cb509..89d4182422 100644
--- a/libs/gtkmm2ext/gtkmm2ext/colors.h
+++ b/libs/gtkmm2ext/gtkmm2ext/colors.h
@@ -115,8 +115,8 @@ struct LIBGTKMM2EXT_API HSV
 	double distance (const HSV& other) const;
 	HSV delta (const HSV& other) const;
 
-	HSV darker (double factor = 1.3) const { return shade (factor); }
-	HSV lighter (double factor = 0.7) const { return shade (factor); }
+	HSV darker (double factor = 1.3) const;
+	HSV lighter (double factor = 0.7) const;
 
 	HSV shade (double factor) const;
 	HSV mix (const HSV& other, double amt) const;