diff --git a/libsigrok4DSL/hardware/DSL/dscope.c b/libsigrok4DSL/hardware/DSL/dscope.c
index f137de28..1e29d231 100644
--- a/libsigrok4DSL/hardware/DSL/dscope.c
+++ b/libsigrok4DSL/hardware/DSL/dscope.c
@@ -221,7 +221,14 @@ static GSList *scan(GSList *options)
 
     /* Find all DSCope compatible devices and upload firmware to them. */
 	devices = NULL;
+    devlist = NULL;
+
     libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
+
+    if (devlist == NULL){
+        sr_info("%s: Failed to call libusb_get_device_list(), it returns a null list.", __func__);
+        return NULL;
+    }
     
 	for (i = 0; devlist[i]; i++) 
     {
diff --git a/libsigrok4DSL/hardware/DSL/dslogic.c b/libsigrok4DSL/hardware/DSL/dslogic.c
index 617bd588..20f3b5ee 100644
--- a/libsigrok4DSL/hardware/DSL/dslogic.c
+++ b/libsigrok4DSL/hardware/DSL/dslogic.c
@@ -314,6 +314,7 @@ static GSList *scan(GSList *options)
 			break;
 		}
 	}
+
 	if (conn){
         sr_info("%s", "Find usb device with connect config.");
         conn_devices = sr_usb_find(drvc->sr_ctx->libusb_ctx, conn);
@@ -323,8 +324,15 @@ static GSList *scan(GSList *options)
 
     /* Find all DSLogic compatible devices and upload firmware to them. */
 	devices = NULL;
+    devlist = NULL;
+    
     libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
     
+    if (devlist == NULL){
+        sr_info("%s: Failed to call libusb_get_device_list(), it returns a null list.", __func__);
+        return NULL;
+    }
+    
 	for (i = 0; devlist[i]; i++) 
     {
         device_handle = devlist[i];
diff --git a/libsigrok4DSL/hardware/common/usb.c b/libsigrok4DSL/hardware/common/usb.c
index 7d5a21a7..8090135b 100644
--- a/libsigrok4DSL/hardware/common/usb.c
+++ b/libsigrok4DSL/hardware/common/usb.c
@@ -105,7 +105,15 @@ SR_PRIV GSList *sr_usb_find(libusb_context *usb_ctx, const char *conn)
 
     /* Looks like a valid USB device specification, but is it connected? */
     devices = NULL;
+    devlist = NULL;
+
     libusb_get_device_list(usb_ctx, &devlist);
+
+    if (devlist == NULL){
+        sr_info("%s: Failed to call libusb_get_device_list(), it returns a null list.", __func__);
+        return NULL;
+    }
+
     for (i = 0; devlist[i]; i++) {
         if ((ret = libusb_get_device_descriptor(devlist[i], &des))) {
             sr_err("Failed to get device descriptor: %s.",
@@ -156,7 +164,15 @@ SR_PRIV GSList *sr_usb_find_usbtmc(libusb_context *usb_ctx)
     int confidx, intfidx, ret, i;
 
     devices = NULL;
+    devlist = NULL;
+
     libusb_get_device_list(usb_ctx, &devlist);
+
+    if (devlist == NULL){
+        sr_info("%s: Failed to call libusb_get_device_list(), it returns a null list.", __func__);
+        return NULL;
+    }
+    
     for (i = 0; devlist[i]; i++) {
         if ((ret = libusb_get_device_descriptor(devlist[i], &des))) {
             sr_err("Failed to get device descriptor: %s.",
diff --git a/libsigrok4DSL/hwdriver.c b/libsigrok4DSL/hwdriver.c
index 1ac7b60f..8d62a633 100644
--- a/libsigrok4DSL/hwdriver.c
+++ b/libsigrok4DSL/hwdriver.c
@@ -388,6 +388,11 @@ SR_PRIV int ds_scan_all_device_list(libusb_context *usb_ctx,struct libusb_device
 	wr = 0;
 	libusb_get_device_list(usb_ctx, &devlist);
 
+	if (devlist == NULL){
+        sr_info("%s: Failed to call libusb_get_device_list(), it returns a null list.", __func__);
+        return NULL;
+    }
+
 	for (i = 0; devlist[i]; i++) 
 	{ 
         ret = libusb_get_device_descriptor(devlist[i], &des);