diff --git a/src/emitterstate.cpp b/src/emitterstate.cpp
index 469040f..124dc1c 100644
--- a/src/emitterstate.cpp
+++ b/src/emitterstate.cpp
@@ -127,7 +127,10 @@ void EmitterState::StartedGroup(GroupType::value type) {
   std::unique_ptr<Group> pGroup(new Group(type));
 
   // transfer settings (which last until this group is done)
-  pGroup->modifiedSettings = m_modifiedSettings;
+  //
+  // NB: if pGroup->modifiedSettings == m_modifiedSettings,
+  // m_modifiedSettings is not changed!
+  pGroup->modifiedSettings = std::move(m_modifiedSettings);
 
   // set up group
   if (GetFlowType(type) == Block)
@@ -136,7 +139,7 @@ void EmitterState::StartedGroup(GroupType::value type) {
     pGroup->flowType = FlowType::Flow;
   pGroup->indent = GetIndent();
 
-  m_groups.push(pGroup);
+  m_groups.push(std::move(pGroup));
 }
 
 void EmitterState::EndedGroup(GroupType::value type) {
diff --git a/src/ptr_stack.h b/src/ptr_stack.h
index 3757432..7767813 100644
--- a/src/ptr_stack.h
+++ b/src/ptr_stack.h
@@ -18,36 +18,40 @@ template <typename T>
 class ptr_stack : private YAML::noncopyable {
  public:
   ptr_stack() {}
-  ~ptr_stack() { clear(); }
 
   void clear() {
-    for (std::size_t i = 0; i < m_data.size(); i++)
-      delete m_data[i];
     m_data.clear();
   }
 
   std::size_t size() const { return m_data.size(); }
   bool empty() const { return m_data.empty(); }
 
-  void push(std::unique_ptr<T> &t) {
-    m_data.push_back(NULL);
-    m_data.back() = t.release();
+  void push(std::unique_ptr<T>&& t) {
+    m_data.push_back(std::move(t));
   }
   std::unique_ptr<T> pop() {
-    std::unique_ptr<T> t(m_data.back());
+   std::unique_ptr<T> t(std::move(m_data.back()));
     m_data.pop_back();
     return t;
   }
-  T& top() { return *m_data.back(); }
-  const T& top() const { return *m_data.back(); }
 
-  T& top(std::ptrdiff_t diff) { return **(m_data.end() - 1 + diff); }
+  T& top() {
+    return *(m_data.back().get());
+  }
+  const T& top() const {
+    return *(m_data.back().get());
+  }
+
+  T& top(std::ptrdiff_t diff) {
+    return *((m_data.end() - 1 + diff)->get());
+  }
+
   const T& top(std::ptrdiff_t diff) const {
-    return **(m_data.end() - 1 + diff);
+    return *((m_data.end() - 1 + diff)->get());
   }
 
  private:
-  std::vector<T*> m_data;
+    std::vector<std::unique_ptr<T>> m_data;
 };
 
 #endif  // PTR_STACK_H_62B23520_7C8E_11DE_8A39_0800200C9A66
diff --git a/src/ptr_vector.h b/src/ptr_vector.h
index de4f8c4..b592ccd 100644
--- a/src/ptr_vector.h
+++ b/src/ptr_vector.h
@@ -20,29 +20,30 @@ template <typename T>
 class ptr_vector : private YAML::noncopyable {
  public:
   ptr_vector() {}
-  ~ptr_vector() { clear(); }
 
   void clear() {
-    for (std::size_t i = 0; i < m_data.size(); i++)
-      delete m_data[i];
     m_data.clear();
   }
 
   std::size_t size() const { return m_data.size(); }
   bool empty() const { return m_data.empty(); }
 
-  void push_back(std::unique_ptr<T> &t) {
-    m_data.push_back(NULL);
-    m_data.back() = t.release();
+  void push_back(std::unique_ptr<T>&& t) {
+    m_data.push_back(std::move(t));
   }
   T& operator[](std::size_t i) { return *m_data[i]; }
   const T& operator[](std::size_t i) const { return *m_data[i]; }
 
-  T& back() { return *m_data.back(); }
-  const T& back() const { return *m_data.back(); }
+  T& back() {
+      return *(m_data.back().get());
+  }
+
+  const T& back() const {
+      return *(m_data.back().get());
+  }
 
  private:
-  std::vector<T*> m_data;
+   std::vector<std::unique_ptr<T>> m_data;
 };
 }
 
diff --git a/src/scanner.cpp b/src/scanner.cpp
index f89ed9b..767b8e1 100644
--- a/src/scanner.cpp
+++ b/src/scanner.cpp
@@ -234,7 +234,7 @@ void Scanner::StartStream() {
   m_startedStream = true;
   m_simpleKeyAllowed = true;
   std::unique_ptr<IndentMarker> pIndent(new IndentMarker(-1, IndentMarker::NONE));
-  m_indentRefs.push_back(pIndent);
+  m_indentRefs.push_back(std::move(pIndent));
   m_indents.push(&m_indentRefs.back());
 }
 
@@ -298,7 +298,7 @@ Scanner::IndentMarker* Scanner::PushIndentTo(int column,
 
   // and then the indent
   m_indents.push(&indent);
-  m_indentRefs.push_back(pIndent);
+  m_indentRefs.push_back(std::move(pIndent));
   return &m_indentRefs.back();
 }
 
diff --git a/src/setting.h b/src/setting.h
index 508193e..b78d40e 100644
--- a/src/setting.h
+++ b/src/setting.h
@@ -62,10 +62,6 @@ class SettingChanges : private noncopyable {
 
   void clear() {
     restore();
-
-    for (setting_changes::const_iterator it = m_settingChanges.begin();
-         it != m_settingChanges.end(); ++it)
-      delete *it;
     m_settingChanges.clear();
   }
 
@@ -76,22 +72,22 @@ class SettingChanges : private noncopyable {
   }
 
   void push(std::unique_ptr<SettingChangeBase> pSettingChange) {
-    m_settingChanges.push_back(pSettingChange.release());
+    m_settingChanges.push_back(std::move(pSettingChange));
   }
 
   // like std::unique_ptr - assignment is transfer of ownership
-  SettingChanges& operator=(SettingChanges& rhs) {
+  SettingChanges& operator=(SettingChanges&& rhs) {
     if (this == &rhs)
       return *this;
 
     clear();
-    m_settingChanges = rhs.m_settingChanges;
-    rhs.m_settingChanges.clear();
+    std::swap(m_settingChanges, rhs.m_settingChanges);
+
     return *this;
   }
 
  private:
-  typedef std::vector<SettingChangeBase*> setting_changes;
+  typedef std::vector<std::unique_ptr<SettingChangeBase>> setting_changes;
   setting_changes m_settingChanges;
 };
 }