diff --git a/platform/libusb/hci_transport_h2_libusb.c b/platform/libusb/hci_transport_h2_libusb.c
index 873027b52..285ce857e 100644
--- a/platform/libusb/hci_transport_h2_libusb.c
+++ b/platform/libusb/hci_transport_h2_libusb.c
@@ -227,6 +227,9 @@ static int sco_out_addr;
 static int usb_path_len;
 static uint8_t usb_path[USB_MAX_PATH_LEN];
 
+// transport interface state
+static int usb_transport_open;
+
 
 #ifdef ENABLE_SCO_OVER_HCI
 static void sco_ring_init(void){
@@ -921,6 +924,8 @@ static void usb_sco_stop(void){
 static int usb_open(void){
     int r;
 
+    if (usb_transport_open) return 0;
+
     handle_packet = NULL;
 
     // default endpoint addresses
@@ -1113,6 +1118,8 @@ static int usb_open(void){
         usb_timer_active = 1;
     }
 
+    usb_transport_open = 1;
+
     return 0;
 }
 
@@ -1120,6 +1127,8 @@ static int usb_close(void){
     int c;
     int completed = 0;
 
+    if (!usb_transport_open) return 0;
+
     log_info("usb_close");
 
     switch (libusb_state){
@@ -1252,6 +1261,7 @@ static int usb_close(void){
 
     libusb_state = LIB_USB_CLOSED;
     handle = NULL;
+    usb_transport_open = 0;
 
     return 0;
 }
diff --git a/platform/windows/hci_transport_h2_winusb.c b/platform/windows/hci_transport_h2_winusb.c
index cf8076ce0..f4b0e47e0 100644
--- a/platform/windows/hci_transport_h2_winusb.c
+++ b/platform/windows/hci_transport_h2_winusb.c
@@ -251,6 +251,8 @@ static int usb_acl_out_active;
 static uint8_t hci_event_in_buffer[2 + 255];
 static uint8_t hci_acl_in_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + HCI_ACL_BUFFER_SIZE]; 
 
+// transport interface state
+static int usb_transport_open;
 
 #ifdef ENABLE_SCO_OVER_HCI
 
@@ -1078,6 +1080,8 @@ static BOOL usb_lookup_symbols(void){
 // returns 0 on success, -1 otherwise
 static int usb_open(void){
 
+    if (usb_transport_open) return 0;
+
     int r = -1;
 
 #ifdef ENABLE_SCO_OVER_HCI
@@ -1200,13 +1204,20 @@ static int usb_open(void){
 
 	SetupDiDestroyDeviceInfoList(hDevInfo);
 
-	log_info("usb_open: done");
+	log_info("usb_open: done, r = %x", r);
+
+    if (r == 0){
+        // opened
+        usb_transport_open = 1;
+    }
 
     return r;    
 }
 
 static int usb_close(void){
     
+    if (!usb_transport_open == 0) return 0;
+
     // remove data sources
     btstack_run_loop_remove_data_source(&usb_data_source_command_out);
     btstack_run_loop_remove_data_source(&usb_data_source_event_in);
@@ -1246,6 +1257,10 @@ static int usb_close(void){
 
     // free everything
     usb_free_resources();
+
+    // transport closed
+    usb_transport_open = 0;
+    
     return 0;    
 }