diff --git a/boards/cc2538dk/dist/flash.sh b/boards/cc2538dk/dist/flash.sh
index 49e0635358..b608ce19be 100755
--- a/boards/cc2538dk/dist/flash.sh
+++ b/boards/cc2538dk/dist/flash.sh
@@ -12,7 +12,7 @@ HEXFILE=$2
 FLASHADDR=200000
 
 # setup JLink command file
-echo "speed 1000" >> $BINDIR/burn.seg
+echo "speed 1000" > $BINDIR/burn.seg
 echo "loadbin $HEXFILE $FLASHADDR" >> $BINDIR/burn.seg
 echo "r" >> $BINDIR/burn.seg
 echo "g" >> $BINDIR/burn.seg
diff --git a/boards/remote/dist/flash.sh b/boards/remote/dist/flash.sh
index 49e0635358..b608ce19be 100755
--- a/boards/remote/dist/flash.sh
+++ b/boards/remote/dist/flash.sh
@@ -12,7 +12,7 @@ HEXFILE=$2
 FLASHADDR=200000
 
 # setup JLink command file
-echo "speed 1000" >> $BINDIR/burn.seg
+echo "speed 1000" > $BINDIR/burn.seg
 echo "loadbin $HEXFILE $FLASHADDR" >> $BINDIR/burn.seg
 echo "r" >> $BINDIR/burn.seg
 echo "g" >> $BINDIR/burn.seg