diff --git a/boards/slstk3401a/Makefile.include b/boards/slstk3401a/Makefile.include
index 260acdf982..55d8eaef3b 100644
--- a/boards/slstk3401a/Makefile.include
+++ b/boards/slstk3401a/Makefile.include
@@ -7,6 +7,7 @@ include $(RIOTMAKE)/tools/serial.inc.mk
 
 # setup JLink for flashing
 export JLINK_DEVICE := $(CPU_MODEL)
+export JLINK_PRE_FLASH = r
 include $(RIOTMAKE)/tools/jlink.inc.mk
 
 # add board common drivers
diff --git a/boards/slstk3402a/Makefile.include b/boards/slstk3402a/Makefile.include
index 260acdf982..55d8eaef3b 100644
--- a/boards/slstk3402a/Makefile.include
+++ b/boards/slstk3402a/Makefile.include
@@ -7,6 +7,7 @@ include $(RIOTMAKE)/tools/serial.inc.mk
 
 # setup JLink for flashing
 export JLINK_DEVICE := $(CPU_MODEL)
+export JLINK_PRE_FLASH = r
 include $(RIOTMAKE)/tools/jlink.inc.mk
 
 # add board common drivers