diff --git a/nfc/1.0/default/Nfc.cpp b/nfc/1.0/default/Nfc.cpp
index c610406..d337a36 100644
--- a/nfc/1.0/default/Nfc.cpp
+++ b/nfc/1.0/default/Nfc.cpp
@@ -12,7 +12,7 @@
 namespace V1_0 {
 namespace implementation {
 
-sp<INfcClientCallback> Nfc::mCallback = NULL;
+sp<INfcClientCallback> Nfc::mCallback = nullptr;
 
 Nfc::Nfc(nfc_nci_device_t* device) : mDevice(device),
     mDeathRecipient(new NfcDeathRecipient(this)) {
@@ -21,35 +21,58 @@
 // Methods from ::android::hardware::nfc::V1_0::INfc follow.
 ::android::hardware::Return<NfcStatus> Nfc::open(const sp<INfcClientCallback>& clientCallback)  {
     mCallback = clientCallback;
+
+    if (mDevice == nullptr || mCallback == nullptr) {
+        return NfcStatus::FAILED;
+    }
     mCallback->linkToDeath(mDeathRecipient, 0 /*cookie*/);
     int ret = mDevice->open(mDevice, eventCallback, dataCallback);
     return ret == 0 ? NfcStatus::OK : NfcStatus::FAILED;
 }
 
 ::android::hardware::Return<uint32_t> Nfc::write(const hidl_vec<uint8_t>& data)  {
+    if (mDevice == nullptr) {
+        return -1;
+    }
     return mDevice->write(mDevice, data.size(), &data[0]);
 }
 
 ::android::hardware::Return<NfcStatus> Nfc::coreInitialized(const hidl_vec<uint8_t>& data)  {
     hidl_vec<uint8_t> copy = data;
+
+    if (mDevice == nullptr) {
+        return NfcStatus::FAILED;
+    }
     int ret = mDevice->core_initialized(mDevice, &copy[0]);
     return ret == 0 ? NfcStatus::OK : NfcStatus::FAILED;
 }
 
 ::android::hardware::Return<NfcStatus> Nfc::prediscover()  {
+    if (mDevice == nullptr) {
+        return NfcStatus::FAILED;
+    }
     return mDevice->pre_discover(mDevice) ? NfcStatus::FAILED : NfcStatus::OK;
 }
 
 ::android::hardware::Return<NfcStatus> Nfc::close()  {
+    if (mDevice == nullptr || mCallback == nullptr) {
+        return NfcStatus::FAILED;
+    }
     mCallback->unlinkToDeath(mDeathRecipient);
     return mDevice->close(mDevice) ? NfcStatus::FAILED : NfcStatus::OK;
 }
 
 ::android::hardware::Return<NfcStatus> Nfc::controlGranted()  {
+    if (mDevice == nullptr) {
+        return NfcStatus::FAILED;
+    }
     return mDevice->control_granted(mDevice) ? NfcStatus::FAILED : NfcStatus::OK;
 }
 
 ::android::hardware::Return<NfcStatus> Nfc::powerCycle()  {
+    if (mDevice == nullptr) {
+        return NfcStatus::FAILED;
+    }
     return mDevice->power_cycle(mDevice) ? NfcStatus::FAILED : NfcStatus::OK;
 }
 
@@ -57,11 +80,10 @@
 INfc* HIDL_FETCH_INfc(const char * /*name*/) {
     nfc_nci_device_t* nfc_device;
     int ret = 0;
-    const hw_module_t* hw_module = NULL;
+    const hw_module_t* hw_module = nullptr;
 
     ret = hw_get_module (NFC_NCI_HARDWARE_MODULE_ID, &hw_module);
-    if (ret == 0)
-    {
+    if (ret == 0) {
         ret = nfc_nci_open (hw_module, &nfc_device);
         if (ret != 0) {
             ALOGE ("nfc_nci_open failed: %d", ret);