diff --git a/media/mtp/MtpObjectInfo.h b/media/mtp/MtpObjectInfo.h
index 86780f1..188f21c 100644
--- a/media/mtp/MtpObjectInfo.h
+++ b/media/mtp/MtpObjectInfo.h
@@ -47,7 +47,7 @@
     char*               mKeywords;
 
 public:
-                        MtpObjectInfo(MtpObjectHandle handle);
+    explicit            MtpObjectInfo(MtpObjectHandle handle);
     virtual             ~MtpObjectInfo();
 
     bool                read(MtpDataPacket& packet);
diff --git a/media/mtp/MtpPacket.h b/media/mtp/MtpPacket.h
index 037722a..cca2783 100644
--- a/media/mtp/MtpPacket.h
+++ b/media/mtp/MtpPacket.h
@@ -35,7 +35,7 @@
     size_t              mPacketSize;
 
 public:
-                        MtpPacket(int bufferSize);
+    explicit            MtpPacket(int bufferSize);
     virtual             ~MtpPacket();
 
     // sets packet size to the default container size and sets buffer to zero
diff --git a/media/mtp/MtpStorageInfo.h b/media/mtp/MtpStorageInfo.h
index 35a8189..3b70675 100644
--- a/media/mtp/MtpStorageInfo.h
+++ b/media/mtp/MtpStorageInfo.h
@@ -36,7 +36,7 @@
     char*               mVolumeIdentifier;
 
 public:
-                        MtpStorageInfo(MtpStorageID id);
+    explicit            MtpStorageInfo(MtpStorageID id);
     virtual             ~MtpStorageInfo();
 
     bool                read(MtpDataPacket& packet);
diff --git a/media/mtp/MtpStringBuffer.h b/media/mtp/MtpStringBuffer.h
index 85d91e8..bcf2a48 100644
--- a/media/mtp/MtpStringBuffer.h
+++ b/media/mtp/MtpStringBuffer.h
@@ -38,8 +38,8 @@
 
 public:
                     MtpStringBuffer();
-                    MtpStringBuffer(const char* src);
-                    MtpStringBuffer(const uint16_t* src);
+    explicit        MtpStringBuffer(const char* src);
+    explicit        MtpStringBuffer(const uint16_t* src);
                     MtpStringBuffer(const MtpStringBuffer& src);
     virtual         ~MtpStringBuffer();