diff --git a/src/ascii_cmd.h b/src/ascii_cmd.h
index fb8e8d4..7584f7b 100644
--- a/src/ascii_cmd.h
+++ b/src/ascii_cmd.h
@@ -1,3 +1,4 @@
+#include "modulator.h"
 #define CMD_BUFFER_SIZE	255
 #define CTL_BUFFER_SIZE	(CMD_BUFFER_SIZE * 2)
 #define READ_TIMEOUT_MS	100