diff --git a/tools/gencert/gencert.sh b/tools/gencert/gencert.sh
index 12ba6db..2df4f9b 100755
--- a/tools/gencert/gencert.sh
+++ b/tools/gencert/gencert.sh
@@ -15,6 +15,9 @@ pub=$2
 cert=$3
 
 hex2pubkey $pub pubkey.pem
+[[ "$?" -ne "0" ]] && exit 1
 signcert $key pubkey.pem $cert
+[[ "$?" -ne "0" ]] && exit 1
 cbytes.py $cert
+[[ "$?" -ne "0" ]] && exit 1
 
diff --git a/tools/setup_device.sh b/tools/setup_device.sh
index 41a17f9..bf7b0dd 100755
--- a/tools/setup_device.sh
+++ b/tools/setup_device.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-SETUP_HEX=../firmware/release/SETUP.hex
+SETUP_HEX=../firmware/SETUP.hex
 FINAL_HEX=../firmware/release/u2f-firmware.hex
 
 if [[ $# != "1" ]]
@@ -13,19 +13,24 @@ fi
 
 export PATH=$PATH:gencert:u2f_zero_client:flashing
 
-# setup atecc
-echo "erasing..."
-erase.sh
+if [[ "$(python -c 'import os,sys; sys.stdout.write(os.name)')" == "nt" ]] 
+then
 
-while [[ "$?" -ne "0" ]] ; do
-    sleep .1
+    # setup atecc
+    echo "erasing..."
     erase.sh
-done
 
-echo "programming setup..."
-program.sh $SETUP_HEX
+    while [[ "$?" -ne "0" ]] ; do
+        sleep .1
+        erase.sh
+    done
 
-[[ "$?" -ne "0" ]] && exit 1
+    echo "programming setup..."
+    program.sh $SETUP_HEX
+
+    [[ "$?" -ne "0" ]] && exit 1
+
+fi
 
 echo "configuring..."
 client.py configure pubkey.hex >/dev/null
@@ -41,6 +46,7 @@ gencert.sh "$1" "$(cat pubkey.hex)" attest.der > ../firmware/src/cert.c
 
 [[ "$?" -ne "0" ]] && exit 1
 
+echo "done."
 echo "building..."
 
 if [[ "$(python -c 'import os,sys; sys.stdout.write(os.name)')" != "nt" ]] 
diff --git a/tools/u2f_zero_client/client.py b/tools/u2f_zero_client/client.py
index 4d9014e..f89bffe 100755
--- a/tools/u2f_zero_client/client.py
+++ b/tools/u2f_zero_client/client.py
@@ -18,9 +18,7 @@ except:
     sys.exit(1)
 
 
-cmd_prefix = [0xff,0xff,0xff,0xff]
-if os.name == 'ns':
-    cmd_prefix.insert(0,0)
+cmd_prefix = [0, 0xff,0xff,0xff,0xff]
 
 class commands:
     U2F_CONFIG_GET_SERIAL_NUM = 0x80