diff --git a/src/gui_gtk_x11.c b/src/gui_gtk_x11.c
index 5837c0b..480b8d3 100644
--- a/src/gui_gtk_x11.c
+++ b/src/gui_gtk_x11.c
@@ -5606,16 +5606,34 @@
     return name != NULL ? gui_get_color_cmn(name) : INVALCOLOR;
 #else
     guicolor_T color;
-    GdkColor gcolor;
-    int ret;
 
     color = (name != NULL) ? gui_get_color_cmn(name) : INVALCOLOR;
     if (color == INVALCOLOR)
 	return INVALCOLOR;
 
-    gcolor.red = (guint16)(((color & 0xff0000) >> 16) / 255.0 * 65535 + 0.5);
-    gcolor.green = (guint16)(((color & 0xff00) >> 8) / 255.0 * 65535 + 0.5);
-    gcolor.blue = (guint16)((color & 0xff) / 255.0 * 65535 + 0.5);
+    return gui_mch_get_rgb_color(
+	    (color & 0xff0000) >> 16,
+	    (color & 0xff00) >> 8,
+	    color & 0xff);
+#endif
+}
+
+/*
+ * Return the Pixel value (color) for the given RGB values.
+ * Return INVALCOLOR for error.
+ */
+    guicolor_T
+gui_mch_get_rgb_color(int r, int g, int b)
+{
+#if GTK_CHECK_VERSION(3,0,0)
+    return gui_get_rgb_color_cmn(r, g, b);
+#else
+    GdkColor gcolor;
+    int ret;
+
+    gcolor.red = (guint16)(r / 255.0 * 65535 + 0.5);
+    gcolor.green = (guint16)(g / 255.0 * 65535 + 0.5);
+    gcolor.blue = (guint16)(b / 255.0 * 65535 + 0.5);
 
     ret = gdk_colormap_alloc_color(gtk_widget_get_colormap(gui.drawarea),
 	    &gcolor, FALSE, TRUE);