diff --git a/core/wiki/macros/CSS.tid b/core/wiki/macros/CSS.tid
index a5b68ea07..563f917a9 100644
--- a/core/wiki/macros/CSS.tid
+++ b/core/wiki/macros/CSS.tid
@@ -2,7 +2,7 @@ title: $:/core/macros/CSS
 tags: $:/tags/Macro
 
 \define colour(name)
-<$transclude tiddler={{$:/palette}} index="$name$"><$transclude tiddler="$:/palettes/Vanilla" index="$name$"/></$transclude>
+<$transclude tiddler={{$:/palette}} index="$name$"><$transclude tiddler="$:/palettes/Vanilla" index="$name$"><$transclude tiddler="$:/config/DefaultColourMappings/$name$"/></$transclude></$transclude>
 \end
 
 \define color(name)
diff --git a/editions/tw5.com/tiddlers/macros/ColourMacro.tid b/editions/tw5.com/tiddlers/macros/ColourMacro.tid
index d63bcb3ec..584556fc7 100644
--- a/editions/tw5.com/tiddlers/macros/ColourMacro.tid
+++ b/editions/tw5.com/tiddlers/macros/ColourMacro.tid
@@ -1,5 +1,5 @@
 created: 20150221154058000
-modified: 20150221154522000
+modified: 20200228142855357
 tags: Macros [[Core Macros]]
 title: colour Macro
 type: text/vnd.tiddlywiki
@@ -7,7 +7,7 @@ caption: colour
 
 The <<.def colour>> (or <<.def color>>) [[macro|Macros]] returns the [[CSS|Cascading Style Sheets]] value of one the colours in the current [[palette|ColourPalettes]].
 
-If no such entry exists in the current palette, the [[vanilla palette|$:/palettes/Vanilla]] is used instead.
+If no such entry exists in the current palette, the [[vanilla palette|$:/palettes/Vanilla]] is used instead. If no such entry exists in the vanilla palette, the system looks for a configuration tiddler with the title `$:/config/DefaultColourMappings/<colour-name>` and transcludes the colour from the text field. This enables to plugins to ship defaults for colours that are not present in the core palettes.
 
 !! Parameters