diff --git a/platform/esb/buildscripts/Makefile.win b/platform/esb/buildscripts/Makefile.win
index edf3b615d..655a3d81e 100644
--- a/platform/esb/buildscripts/Makefile.win
+++ b/platform/esb/buildscripts/Makefile.win
@@ -1,5 +1,9 @@
 %.u:	%.ihex
+ifdef JTAG_PORT
+	msp430-jtag -l $(JTAG_PORT) -eI $^
+else
 	msp430-jtag -eI $^
+endif
 
 #CW=cw23