diff --git a/include/utils/Condition.h b/include/utils/Condition.h
index a420185..5650598 100644
--- a/include/utils/Condition.h
+++ b/include/utils/Condition.h
@@ -54,7 +54,7 @@
     };
 
     Condition();
-    Condition(int type);
+    explicit Condition(int type);
     ~Condition();
     // Wait on the condition variable.  Lock the mutex before calling.
     status_t wait(Mutex& mutex);
diff --git a/include/utils/Mutex.h b/include/utils/Mutex.h
index f027c79..8b720b9 100644
--- a/include/utils/Mutex.h
+++ b/include/utils/Mutex.h
@@ -48,8 +48,8 @@
     };
 
                 Mutex();
-                Mutex(const char* name);
-                Mutex(int type, const char* name = NULL);
+    explicit    Mutex(const char* name);
+    explicit    Mutex(int type, const char* name = NULL);
                 ~Mutex();
 
     // lock or unlock the mutex
@@ -73,8 +73,8 @@
     // constructed and released when Autolock goes out of scope.
     class Autolock {
     public:
-        inline Autolock(Mutex& mutex) : mLock(mutex)  { mLock.lock(); }
-        inline Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
+        inline explicit Autolock(Mutex& mutex) : mLock(mutex)  { mLock.lock(); }
+        inline explicit Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
         inline ~Autolock() { mLock.unlock(); }
     private:
         Mutex& mLock;
diff --git a/include/utils/RWLock.h b/include/utils/RWLock.h
index e743b1c..d5b81d3 100644
--- a/include/utils/RWLock.h
+++ b/include/utils/RWLock.h
@@ -47,8 +47,8 @@
     };
 
                 RWLock();
-                RWLock(const char* name);
-                RWLock(int type, const char* name = NULL);
+    explicit    RWLock(const char* name);
+    explicit    RWLock(int type, const char* name = NULL);
                 ~RWLock();
 
     status_t    readLock();
@@ -59,7 +59,7 @@
 
     class AutoRLock {
     public:
-        inline AutoRLock(RWLock& rwlock) : mLock(rwlock)  { mLock.readLock(); }
+        inline explicit AutoRLock(RWLock& rwlock) : mLock(rwlock)  { mLock.readLock(); }
         inline ~AutoRLock() { mLock.unlock(); }
     private:
         RWLock& mLock;
@@ -67,7 +67,7 @@
 
     class AutoWLock {
     public:
-        inline AutoWLock(RWLock& rwlock) : mLock(rwlock)  { mLock.writeLock(); }
+        inline explicit AutoWLock(RWLock& rwlock) : mLock(rwlock)  { mLock.writeLock(); }
         inline ~AutoWLock() { mLock.unlock(); }
     private:
         RWLock& mLock;
diff --git a/include/utils/RefBase.h b/include/utils/RefBase.h
index c82e7d9..950dbd0 100644
--- a/include/utils/RefBase.h
+++ b/include/utils/RefBase.h
@@ -222,12 +222,12 @@
     
     inline wp() : m_ptr(0) { }
 
-    wp(T* other);
+    wp(T* other);  // NOLINT(implicit)
     wp(const wp<T>& other);
-    wp(const sp<T>& other);
-    template<typename U> wp(U* other);
-    template<typename U> wp(const sp<U>& other);
-    template<typename U> wp(const wp<U>& other);
+    explicit wp(const sp<T>& other);
+    template<typename U> wp(U* other);  // NOLINT(implicit)
+    template<typename U> wp(const sp<U>& other);  // NOLINT(implicit)
+    template<typename U> wp(const wp<U>& other);  // NOLINT(implicit)
 
     ~wp();
     
diff --git a/include/utils/StrongPointer.h b/include/utils/StrongPointer.h
index 50fde35..d90b788 100644
--- a/include/utils/StrongPointer.h
+++ b/include/utils/StrongPointer.h
@@ -60,12 +60,12 @@
 public:
     inline sp() : m_ptr(0) { }
 
-    sp(T* other);
+    sp(T* other);  // NOLINT(implicit)
     sp(const sp<T>& other);
     sp(sp<T>&& other);
-    template<typename U> sp(U* other);
-    template<typename U> sp(const sp<U>& other);
-    template<typename U> sp(sp<U>&& other);
+    template<typename U> sp(U* other);  // NOLINT(implicit)
+    template<typename U> sp(const sp<U>& other);  // NOLINT(implicit)
+    template<typename U> sp(sp<U>&& other);  // NOLINT(implicit)
 
     ~sp();
 
diff --git a/include/utils/Thread.h b/include/utils/Thread.h
index 1532b7e..0f7ac9f 100644
--- a/include/utils/Thread.h
+++ b/include/utils/Thread.h
@@ -41,7 +41,7 @@
 public:
     // Create a Thread object, but doesn't create or start the associated
     // thread. See the run() method.
-                        Thread(bool canCallJava = true);
+    explicit            Thread(bool canCallJava = true);
     virtual             ~Thread();
 
     // Start the thread in threadLoop() which needs to be implemented.
diff --git a/include/utils/TypeHelpers.h b/include/utils/TypeHelpers.h
index 61d618e..64d25c5 100644
--- a/include/utils/TypeHelpers.h
+++ b/include/utils/TypeHelpers.h
@@ -240,7 +240,7 @@
     key_value_pair_t() { }
     key_value_pair_t(const key_value_pair_t& o) : key(o.key), value(o.value) { }
     key_value_pair_t(const KEY& k, const VALUE& v) : key(k), value(v)  { }
-    key_value_pair_t(const KEY& k) : key(k) { }
+    explicit key_value_pair_t(const KEY& k) : key(k) { }
     inline bool operator < (const key_value_pair_t& o) const {
         return strictly_order_type(key, o.key);
     }
diff --git a/include/utils/VectorImpl.h b/include/utils/VectorImpl.h
index 21ad71c..4dd91fd 100644
--- a/include/utils/VectorImpl.h
+++ b/include/utils/VectorImpl.h
@@ -132,7 +132,7 @@
 {
 public:
                             SortedVectorImpl(size_t itemSize, uint32_t flags);
-                            SortedVectorImpl(const VectorImpl& rhs);
+    explicit                SortedVectorImpl(const VectorImpl& rhs);
     virtual                 ~SortedVectorImpl();
     
     SortedVectorImpl&     operator = (const SortedVectorImpl& rhs);