--- a/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
+++ b/dom/media/gmp/widevine-adapter/WidevineDecryptor.cpp
@@ -188,17 +188,17 @@ WidevineDecryptor::DecryptingComplete()
   Log("WidevineDecryptor::DecryptingComplete() this=%p", this);
   mCDM = nullptr;
   mCallback = nullptr;
   Release();
 }
 
 class WidevineBuffer : public cdm::Buffer {
 public:
-  WidevineBuffer(size_t aSize) {
+  explicit WidevineBuffer(size_t aSize) {
     Log("WidevineBuffer(size=" PRIuSIZE ") created", aSize);
     mBuffer.SetLength(aSize);
   }
   ~WidevineBuffer() {
     Log("WidevineBuffer(size=" PRIuSIZE ") destroyed", Size());
   }
   void Destroy() override { delete this; }
   uint32_t Capacity() const override { return mBuffer.Length(); };

--- a/dom/media/gmp/widevine-adapter/WidevineUtils.h
+++ b/dom/media/gmp/widevine-adapter/WidevineUtils.h
@@ -41,17 +41,17 @@ Log(const char* aFormat, ...);
 
 GMPErr
 ToGMPErr(cdm::Status aStatus);
 
 class CDMWrapper {
 public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CDMWrapper)
 
-  CDMWrapper(cdm::ContentDecryptionModule_8* aCDM)
+  explicit CDMWrapper(cdm::ContentDecryptionModule_8* aCDM)
     : mCDM(aCDM)
   {
     MOZ_ASSERT(mCDM);
   }
   cdm::ContentDecryptionModule_8* GetCDM() const { return mCDM; }
 private:
   cdm::ContentDecryptionModule_8* mCDM;
   ~CDMWrapper() {