diff --git a/board/msba2/Jamrules.msba2 b/board/msba2/Jamrules.msba2
index fdcf4b6f65..5111de74d3 100644
--- a/board/msba2/Jamrules.msba2
+++ b/board/msba2/Jamrules.msba2
@@ -29,5 +29,5 @@ CPU = lpc2387 ;
 
 HDRS += [ FPath $(TOP) board $(BOARD) drivers include ] ;
 
-FLASHER = $(POSIXSHELL) $(TOP)/board/msba2/tools/flashutil.sh ;
-FLASHFLAGS = --basedir $(TOP)/board/msba2/tools --id "MSB-A2" --ports "$(PORT)" ;
+FLASHER ?= $(POSIXSHELL) $(TOP)/board/msba2/tools/flashutil.sh ;
+FLASHFLAGS ?= --basedir $(TOP)/board/msba2/tools --id "MSB-A2" --ports "$(PORT)" ;