diff --git a/usb_application/simtrace.py b/usb_application/simtrace.py
index 49349586..25529ba4 100755
--- a/usb_application/simtrace.py
+++ b/usb_application/simtrace.py
@@ -82,7 +82,7 @@ def main():
 #            ret = dev.read(0x83, 64, 100)
             print(ret)
     if args.sniff is True:
-        sniffer.sniff()
+        sniffer.sniff(dev)
     if args.select_file is True:
         ccid_select.select()
     if args.phone is True:
diff --git a/usb_application/sniffer.py b/usb_application/sniffer.py
index 7ac2dae4..eab8dba8 100755
--- a/usb_application/sniffer.py
+++ b/usb_application/sniffer.py
@@ -49,8 +49,7 @@ def find_eps(dev):
     return (ep_in, ep_out)
 
 # main code
-def sniff():
-    dev = find_dev()
+def sniff(dev):
     ans = array.array('B', [])
 
     apdus = []