diff --git a/boards/telosb/Makefile.include b/boards/telosb/Makefile.include
index f3a088913f..9e69e1cad4 100644
--- a/boards/telosb/Makefile.include
+++ b/boards/telosb/Makefile.include
@@ -11,4 +11,5 @@ include $(RIOTMAKE)/tools/serial.inc.mk
 
 # flash tool configuration
 FLASHER = $(RIOTTOOLS)/goodfet/goodfet.bsl
-FFLAGS = --telosb -c $(PORT) -r -e -I -p $(HEXFILE)
+FLASHFILE ?= $(HEXFILE)
+FFLAGS = --telosb -c $(PORT) -r -e -I -p $(FLASHFILE)
diff --git a/boards/z1/Makefile.include b/boards/z1/Makefile.include
index 7d99332157..fee293002e 100644
--- a/boards/z1/Makefile.include
+++ b/boards/z1/Makefile.include
@@ -10,4 +10,5 @@ include $(RIOTMAKE)/tools/serial.inc.mk
 
 # setup flash tool
 FLASHER = $(RIOTTOOLS)/goodfet/goodfet.bsl
-FFLAGS = --z1 -I -c $(PORT) -r -e -p $(HEXFILE)
+FLASHFILE ?= $(HEXFILE)
+FFLAGS = --z1 -I -c $(PORT) -r -e -p $(FLASHFILE)