diff --git a/keywords.txt b/keywords.txt
index cb5c129cb..be8d533e8 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -32,6 +32,7 @@ attachCts	KEYWORD2
 PROGMEM	LITERAL1
 FLASHMEM	LITERAL1
 DMAMEM	LITERAL1
+EXTMEM	LITERAL1
 FASTRUN	LITERAL1
 Serial4	KEYWORD1
 Serial5	KEYWORD1