diff --git a/headers/os/interface/InterfaceDefs.h b/headers/os/interface/InterfaceDefs.h
index 02b9add674..38587d13b2 100644
--- a/headers/os/interface/InterfaceDefs.h
+++ b/headers/os/interface/InterfaceDefs.h
@@ -331,9 +331,15 @@ enum color_which {
 	B_KEYBOARD_NAVIGATION_COLOR = B_NAVIGATION_BASE_COLOR,
 	B_MENU_SELECTION_BACKGROUND_COLOR = B_MENU_SELECTED_BACKGROUND_COLOR,
 
-	// These are deprecated -- do not use in new code.  See BScreen for
-	// the replacement for B_DESKTOP_COLOR.
+	// Update this constant to be the largest color constant excluding
+	// B_SUCCESS_COLOR and B_FAILURE_COLOR.
+	// If you add a constant with index greater than 100 you'll have to add
+	// to the second operand below and also update ServerReadOnlyMemory.h
+	B_COLOR_WHICH_COUNT = B_SCROLL_BAR_THUMB_COLOR + 3,
+
+	// The following constants are deprecated, do not use in new code.
 	B_DESKTOP_COLOR = 5
+		// see BScreen class for B_DESKTOP_COLOR replacement
 };
 
 
diff --git a/headers/private/app/ServerReadOnlyMemory.h b/headers/private/app/ServerReadOnlyMemory.h
index 46f925ec4e..1401467f63 100644
--- a/headers/private/app/ServerReadOnlyMemory.h
+++ b/headers/private/app/ServerReadOnlyMemory.h
@@ -13,23 +13,18 @@
 #include <InterfaceDefs.h>
 
 
-static const int32 kNumColors = 35;
-
 struct server_read_only_memory {
-	rgb_color	colors[kNumColors];
+	rgb_color	colors[B_COLOR_WHICH_COUNT];
 };
 
 
-// NOTE: these functions must be kept in sync with InterfaceDefs.h color_which!
-
 static inline int32
 color_which_to_index(color_which which)
 {
-	// NOTE: this must be kept in sync with InterfaceDefs.h color_which!
-	if (which <= B_SCROLL_BAR_THUMB_COLOR)
+	if (which <= B_COLOR_WHICH_COUNT - 3)
 		return which - 1;
 	if (which >= B_SUCCESS_COLOR && which <= B_FAILURE_COLOR)
-		return which - B_SUCCESS_COLOR + B_SCROLL_BAR_THUMB_COLOR;
+		return which - B_SUCCESS_COLOR + B_COLOR_WHICH_COUNT - 3;
 
 	return -1;
 }
@@ -38,12 +33,12 @@ color_which_to_index(color_which which)
 static inline color_which
 index_to_color_which(int32 index)
 {
-	if (index >= 0 && index < kNumColors) {
-		if ((color_which)index < B_SCROLL_BAR_THUMB_COLOR)
+	if (index >= 0 && index < B_COLOR_WHICH_COUNT) {
+		if ((color_which)index < B_COLOR_WHICH_COUNT - 3)
 			return (color_which)(index + 1);
 		else {
 			return (color_which)(index + B_SUCCESS_COLOR
-			  - B_SCROLL_BAR_THUMB_COLOR);
+				- B_COLOR_WHICH_COUNT - 3);
 		}
 	}
 
diff --git a/src/kits/interface/InterfaceDefs.cpp b/src/kits/interface/InterfaceDefs.cpp
index 0019676f4a..7744821143 100644
--- a/src/kits/interface/InterfaceDefs.cpp
+++ b/src/kits/interface/InterfaceDefs.cpp
@@ -69,7 +69,7 @@ menu_info *_menu_info_ptr_;
 
 extern "C" const char B_NOTIFICATION_SENDER[] = "be:sender";
 
-static const rgb_color _kDefaultColors[kNumColors] = {
+static const rgb_color _kDefaultColors[B_COLOR_WHICH_COUNT] = {
 	{216, 216, 216, 255},	// B_PANEL_BACKGROUND_COLOR
 	{216, 216, 216, 255},	// B_MENU_BACKGROUND_COLOR
 	{255, 203, 0, 255},		// B_WINDOW_TAB_COLOR
@@ -1071,7 +1071,7 @@ rgb_color
 ui_color(color_which which)
 {
 	int32 index = color_which_to_index(which);
-	if (index < 0 || index >= kNumColors) {
+	if (index < 0 || index >= B_COLOR_WHICH_COUNT) {
 		fprintf(stderr, "ui_color(): unknown color_which %d\n", which);
 		return make_color(0, 0, 0);
 	}
@@ -1090,7 +1090,7 @@ void
 set_ui_color(const color_which &which, const rgb_color &color)
 {
 	int32 index = color_which_to_index(which);
-	if (index < 0 || index >= kNumColors) {
+	if (index < 0 || index >= B_COLOR_WHICH_COUNT) {
 		fprintf(stderr, "set_ui_color(): unknown color_which %d\n", which);
 		return;
 	}
diff --git a/src/servers/app/DesktopSettings.cpp b/src/servers/app/DesktopSettings.cpp
index f5660b914b..12646ae9f3 100644
--- a/src/servers/app/DesktopSettings.cpp
+++ b/src/servers/app/DesktopSettings.cpp
@@ -18,6 +18,7 @@
 #include <Path.h>
 
 #include <DefaultColors.h>
+#include <InterfaceDefs.h>
 #include <ServerReadOnlyMemory.h>
 
 #include "Desktop.h"
@@ -77,7 +78,7 @@ DesktopSettingsPrivate::_SetDefaults()
 	fWorkspacesRows = 2;
 
 	memcpy(fShared.colors, BPrivate::kDefaultColors,
-		sizeof(rgb_color) * kNumColors);
+		sizeof(rgb_color) * B_COLOR_WHICH_COUNT);
 
 	gSubpixelAntialiasing = false;
 	gDefaultHintingMode = HINTING_MODE_ON;
@@ -291,7 +292,7 @@ DesktopSettingsPrivate::_Load()
 			}
 
 			// colors
-			for (int32 i = 0; i < kNumColors; i++) {
+			for (int32 i = 0; i < B_COLOR_WHICH_COUNT; i++) {
 				char colorName[12];
 				snprintf(colorName, sizeof(colorName), "color%" B_PRId32,
 					(int32)index_to_color_which(i));
@@ -436,7 +437,7 @@ DesktopSettingsPrivate::Save(uint32 mask)
 			settings.AddInt8("subpixel average weight", gSubpixelAverageWeight);
 			settings.AddBool("subpixel ordering", gSubpixelOrderingRGB);
 
-			for (int32 i = 0; i < kNumColors; i++) {
+			for (int32 i = 0; i < B_COLOR_WHICH_COUNT; i++) {
 				char colorName[12];
 				snprintf(colorName, sizeof(colorName), "color%" B_PRId32,
 					(int32)index_to_color_which(i));
@@ -648,10 +649,10 @@ DesktopSettingsPrivate::WorkspacesMessage(int32 index) const
 void
 DesktopSettingsPrivate::SetUIColor(color_which which, const rgb_color color)
 {
-	//
 	int32 index = color_which_to_index(which);
-	if (index < 0 || index >= kNumColors)
+	if (index < 0 || index >= B_COLOR_WHICH_COUNT)
 		return;
+
 	fShared.colors[index] = color;
 	// TODO: deprecate the background_color member of the menu_info struct,
 	// otherwise we have to keep this duplication...
@@ -666,7 +667,7 @@ DesktopSettingsPrivate::UIColor(color_which which) const
 {
 	static const rgb_color invalidColor = {0, 0, 0, 0};
 	int32 index = color_which_to_index(which);
-	if (index < 0 || index >= kNumColors)
+	if (index < 0 || index >= B_COLOR_WHICH_COUNT)
 		return invalidColor;
 	return fShared.colors[index];
 }