diff --git a/src/libsysprof-ui/sysprof-marks-aid.c b/src/libsysprof-ui/sysprof-marks-aid.c
index 98744c91..4361dfab 100644
--- a/src/libsysprof-ui/sysprof-marks-aid.c
+++ b/src/libsysprof-ui/sysprof-marks-aid.c
@@ -46,6 +46,177 @@ typedef struct
 
 G_DEFINE_TYPE (SysprofMarksAid, sysprof_marks_aid, SYSPROF_TYPE_AID)
 
+static void
+rgb_to_hls (gdouble *r,
+            gdouble *g,
+            gdouble *b)
+{
+  gdouble min;
+  gdouble max;
+  gdouble red;
+  gdouble green;
+  gdouble blue;
+  gdouble h, l, s;
+  gdouble delta;
+
+  red = *r;
+  green = *g;
+  blue = *b;
+  if (red > green)
+    {
+      if (red > blue)
+        max = red;
+      else
+        max = blue;
+      if (green < blue)
+        min = green;
+      else
+        min = blue;
+    }
+  else
+    {
+      if (green > blue)
+        max = green;
+      else
+        max = blue;
+      if (red < blue)
+        min = red;
+      else
+        min = blue;
+    }
+  l = (max + min) / 2;
+  s = 0;
+  h = 0;
+  if (max != min)
+    {
+      if (l <= 0.5)
+        s = (max - min) / (max + min);
+      else
+        s = (max - min) / (2 - max - min);
+      delta = max - min;
+      if (red == max)
+        h = (green - blue) / delta;
+      else if (green == max)
+        h = 2 + (blue - red) / delta;
+      else if (blue == max)
+        h = 4 + (red - green) / delta;
+      h *= 60;
+      if (h < 0.0)
+        h += 360;
+    }
+  *r = h;
+  *g = l;
+  *b = s;
+}
+
+static void
+hls_to_rgb (gdouble *h,
+            gdouble *l,
+            gdouble *s)
+{
+  gdouble hue;
+  gdouble lightness;
+  gdouble saturation;
+  gdouble m1, m2;
+  gdouble r, g, b;
+
+  lightness = *l;
+  saturation = *s;
+  if (lightness <= 0.5)
+    m2 = lightness * (1 + saturation);
+  else
+    m2 = lightness + saturation - lightness * saturation;
+  m1 = 2 * lightness - m2;
+  if (saturation == 0)
+    {
+      *h = lightness;
+      *l = lightness;
+      *s = lightness;
+    }
+  else
+    {
+      hue = *h + 120;
+      while (hue > 360)
+        hue -= 360;
+      while (hue < 0)
+        hue += 360;
+      if (hue < 60)
+        r = m1 + (m2 - m1) * hue / 60;
+      else if (hue < 180)
+        r = m2;
+      else if (hue < 240)
+        r = m1 + (m2 - m1) * (240 - hue) / 60;
+      else
+        r = m1;
+      hue = *h;
+      while (hue > 360)
+        hue -= 360;
+      while (hue < 0)
+        hue += 360;
+      if (hue < 60)
+        g = m1 + (m2 - m1) * hue / 60;
+      else if (hue < 180)
+        g = m2;
+      else if (hue < 240)
+        g = m1 + (m2 - m1) * (240 - hue) / 60;
+      else
+        g = m1;
+      hue = *h - 120;
+      while (hue > 360)
+        hue -= 360;
+      while (hue < 0)
+        hue += 360;
+      if (hue < 60)
+        b = m1 + (m2 - m1) * hue / 60;
+      else if (hue < 180)
+        b = m2;
+      else if (hue < 240)
+        b = m1 + (m2 - m1) * (240 - hue) / 60;
+      else
+        b = m1;
+      *h = r;
+      *l = g;
+      *s = b;
+    }
+}
+
+static void
+rgba_shade (const GdkRGBA *rgba,
+            GdkRGBA       *dst,
+            gdouble        k)
+{
+  gdouble red;
+  gdouble green;
+  gdouble blue;
+
+  red = rgba->red;
+  green = rgba->green;
+  blue = rgba->blue;
+
+  rgb_to_hls (&red, &green, &blue);
+
+  green *= k;
+
+  if (green > 1.0)
+    green = 1.0;
+  else if (green < 0.0)
+    green = 0.0;
+
+  blue *= k;
+
+  if (blue > 1.0)
+    blue = 1.0;
+  else if (blue < 0.0)
+    blue = 0.0;
+
+  hls_to_rgb (&red, &green, &blue);
+
+  dst->red = red;
+  dst->green = green;
+  dst->blue = blue;
+  dst->alpha = rgba->alpha;
+}
+
 static void
 present_free (gpointer data)
 {
@@ -275,7 +446,7 @@ sysprof_marks_aid_present_finish (SysprofAid    *aid,
 
               if (!g_hash_table_contains (seen, GUINT_TO_POINTER (span->kind)))
                 {
-                  dzl_rgba_shade (&rgba, &kind_rgba, 1 + (ratio * span->kind));
+                  rgba_shade (&rgba, &kind_rgba, 1 + (ratio * span->kind));
                   g_hash_table_insert (seen,
                                        GUINT_TO_POINTER (span->kind),
                                        g_memdup2 (&kind_rgba, sizeof kind_rgba));