diff --git a/build/shared/lib/keywords.txt b/build/shared/lib/keywords.txt
index 16d6d191827..7911901e725 100644
--- a/build/shared/lib/keywords.txt
+++ b/build/shared/lib/keywords.txt
@@ -9,6 +9,7 @@ HIGH	LITERAL2	Constants	RESERVED_WORD_2
 LOW	LITERAL2	Constants	RESERVED_WORD_2
 INPUT	LITERAL2	Constants	RESERVED_WORD_2
 INPUT_PULLUP	LITERAL2	Constants	RESERVED_WORD_2
+INPUT_PULLDOWN	LITERAL2	Constants	RESERVED_WORD_2
 OUTPUT	LITERAL2	Constants	RESERVED_WORD_2
 DEC	LITERAL2	Serial_Print	RESERVED_WORD_2
 BIN	LITERAL2	Serial_Print	RESERVED_WORD_2