diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 71d371f97138..f978aebe60c5 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -222,30 +222,30 @@ static ssize_t config_show(struct device *dev,
 
 	mutex_lock(&test_fw_mutex);
 
-	len += snprintf(buf, PAGE_SIZE,
+	len += scnprintf(buf, PAGE_SIZE - len,
 			"Custom trigger configuration for: %s\n",
 			dev_name(dev));
 
 	if (test_fw_config->name)
-		len += snprintf(buf+len, PAGE_SIZE,
+		len += scnprintf(buf+len, PAGE_SIZE - len,
 				"name:\t%s\n",
 				test_fw_config->name);
 	else
-		len += snprintf(buf+len, PAGE_SIZE,
+		len += scnprintf(buf+len, PAGE_SIZE - len,
 				"name:\tEMTPY\n");
 
-	len += snprintf(buf+len, PAGE_SIZE,
+	len += scnprintf(buf+len, PAGE_SIZE - len,
 			"num_requests:\t%u\n", test_fw_config->num_requests);
 
-	len += snprintf(buf+len, PAGE_SIZE,
+	len += scnprintf(buf+len, PAGE_SIZE - len,
 			"send_uevent:\t\t%s\n",
 			test_fw_config->send_uevent ?
 			"FW_ACTION_HOTPLUG" :
 			"FW_ACTION_NOHOTPLUG");
-	len += snprintf(buf+len, PAGE_SIZE,
+	len += scnprintf(buf+len, PAGE_SIZE - len,
 			"sync_direct:\t\t%s\n",
 			test_fw_config->sync_direct ? "true" : "false");
-	len += snprintf(buf+len, PAGE_SIZE,
+	len += scnprintf(buf+len, PAGE_SIZE - len,
 			"read_fw_idx:\t%u\n", test_fw_config->read_fw_idx);
 
 	mutex_unlock(&test_fw_mutex);