diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index 2e6646a..2174b2f 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -326,7 +326,7 @@
 
     static audio_mode_t getPhoneState();
 
-    static status_t registerPolicyMixes(Vector<AudioMix> mixes, bool registration);
+    static status_t registerPolicyMixes(const Vector<AudioMix>& mixes, bool registration);
 
     static status_t startAudioSource(const struct audio_port_config *source,
                                       const audio_attributes_t *attributes,
diff --git a/include/media/IAudioPolicyService.h b/include/media/IAudioPolicyService.h
index 0e9e3bc..ef15a0c 100644
--- a/include/media/IAudioPolicyService.h
+++ b/include/media/IAudioPolicyService.h
@@ -160,7 +160,7 @@
 
     virtual audio_mode_t getPhoneState() = 0;
 
-    virtual status_t registerPolicyMixes(Vector<AudioMix> mixes, bool registration) = 0;
+    virtual status_t registerPolicyMixes(const Vector<AudioMix>& mixes, bool registration) = 0;
 
     virtual status_t startAudioSource(const struct audio_port_config *source,
                                       const audio_attributes_t *attributes,
diff --git a/include/media/RingBuffer.h b/include/media/RingBuffer.h
index df7c00e..4d92d87 100644
--- a/include/media/RingBuffer.h
+++ b/include/media/RingBuffer.h
@@ -39,7 +39,7 @@
     /**
      * Construct a RingBuffer that can grow up to the given length.
      */
-    RingBuffer(size_t length);
+    explicit RingBuffer(size_t length);
 
     /**
      * Forward iterator to this class.  Implements an std:forward_iterator.
diff --git a/include/media/SharedLibrary.h b/include/media/SharedLibrary.h
index 88451a0..fd02203 100644
--- a/include/media/SharedLibrary.h
+++ b/include/media/SharedLibrary.h
@@ -24,7 +24,7 @@
 namespace android {
     class SharedLibrary : public RefBase {
     public:
-        SharedLibrary(const String8 &path);
+        explicit SharedLibrary(const String8 &path);
         ~SharedLibrary();
 
         bool operator!() const;