diff -ruN claw-orig/claw/impl/avl_base.tpp claw/claw/impl/avl_base.tpp
--- a/claw/impl/avl_base.tpp
+++ b/claw/impl/avl_base.tpp
@@ -1082,7 +1082,7 @@
 typename claw::avl_base<K,Comp>::iterator
 claw::avl_base<K,Comp>::find( const K& key )
 {
-  return make_iterator( m_tree->find(key) );
+  return make_iterator( m_tree ? m_tree->find(key) : NULL );
 } // avl_base::find()
 
 /*----------------------------------------------------------------------------*/
@@ -1094,7 +1094,7 @@
 typename claw::avl_base<K,Comp>::const_iterator
 claw::avl_base<K,Comp>::find( const K& key ) const
 {
-  return make_const_iterator( m_tree->find(key) );
+  return make_const_iterator( m_tree ? m_tree->find(key) : NULL );
 } // avl_base::find()
 
 /*----------------------------------------------------------------------------*/
@@ -1107,7 +1107,7 @@
 typename claw::avl_base<K,Comp>::iterator
 claw::avl_base<K,Comp>::find_nearest_greater( const K& key )
 {
-  return make_iterator( m_tree->find_nearest_greater(key) );
+  return make_iterator( m_tree ? m_tree->find_nearest_greater(key) : NULL );
 } // avl_base::find_nearest_greater()
 
 /*----------------------------------------------------------------------------*/
@@ -1120,7 +1120,7 @@
 typename claw::avl_base<K,Comp>::const_iterator
 claw::avl_base<K,Comp>::find_nearest_greater( const K& key ) const
 {
-  return make_const_iterator( m_tree->find_nearest_greater(key) );
+  return make_const_iterator( m_tree ? m_tree->find_nearest_greater(key) : NULL );
 } // avl_base::find_nearest_greater()
 
 /*----------------------------------------------------------------------------*/
@@ -1133,7 +1133,7 @@
 typename claw::avl_base<K,Comp>::iterator
 claw::avl_base<K,Comp>::find_nearest_lower( const K& key )
 {
-  return make_iterator( m_tree->find_nearest_lower(key) );
+  return make_iterator( m_tree ? m_tree->find_nearest_lower(key) : NULL );
 } // avl_base::find_nearest_lower()
 
 /*----------------------------------------------------------------------------*/
@@ -1146,7 +1146,7 @@
 typename claw::avl_base<K,Comp>::const_iterator
 claw::avl_base<K,Comp>::find_nearest_lower( const K& key ) const
 {
-  return make_const_iterator( m_tree->find_nearest_lower(key) );
+  return make_const_iterator( m_tree ? m_tree->find_nearest_lower(key) : NULL );
 } // avl_base::find_nearest_lower()
 
 /*----------------------------------------------------------------------------*/
@@ -1156,7 +1156,7 @@
 template<class K, class Comp>
 typename claw::avl_base<K,Comp>::iterator claw::avl_base<K,Comp>::lower_bound()
 {
-  return make_iterator( m_tree->lower_bound() );
+  return make_iterator( m_tree ? m_tree->lower_bound() : NULL );
 } // avl_base::lower_bound()
 
 /*----------------------------------------------------------------------------*/
@@ -1167,7 +1167,7 @@
 typename claw::avl_base<K,Comp>::const_iterator
 claw::avl_base<K,Comp>::lower_bound() const
 {
-  return make_const_iterator( m_tree->lower_bound() );
+  return make_const_iterator( m_tree ? m_tree->lower_bound() : NULL );
 } // avl_base::lower_bound()
 
 /*----------------------------------------------------------------------------*/
@@ -1177,7 +1177,7 @@
 template<class K, class Comp>
 typename claw::avl_base<K,Comp>::iterator claw::avl_base<K,Comp>::upper_bound()
 {
-  return make_iterator( m_tree->upper_bound() );
+  return make_iterator( m_tree ? m_tree->upper_bound() : NULL );
 } // avl_base::upper_bound()
 
 /*----------------------------------------------------------------------------*/
@@ -1188,7 +1188,7 @@
 typename claw::avl_base<K,Comp>::const_iterator
 claw::avl_base<K,Comp>::upper_bound() const
 {
-  return make_const_iterator( m_tree->upper_bound() );
+  return make_const_iterator( m_tree ? m_tree->upper_bound() : NULL );
 } // avl_base::upper_bound()
 
 /*----------------------------------------------------------------------------*/
diff -ruN claw-orig/claw/impl/socket_stream.tpp claw/claw/impl/socket_stream.tpp
--- a/claw/impl/socket_stream.tpp
+++ b/claw/impl/socket_stream.tpp
@@ -37,7 +37,7 @@
 template<typename CharT, typename Traits>
 claw::net::basic_socket_stream<CharT, Traits>::basic_socket_stream
 ( int read_delay )
-  : m_buffer(read_delay)
+  : std::basic_iostream<CharT, Traits>(nullptr), m_buffer(read_delay)
 {
   this->init(&m_buffer);
 } // basic_socket_stream::basic_socket_stream()
@@ -53,7 +53,7 @@
 template<typename CharT, typename Traits>
 claw::net::basic_socket_stream<CharT, Traits>::basic_socket_stream
 ( const char* address, int port, int read_delay )
-  : m_buffer(read_delay)
+  : std::basic_iostream<CharT, Traits>(nullptr), m_buffer(read_delay)
 {
   this->init(&m_buffer);
   open(address, port);
diff -ruN claw-orig/claw/it_index.hpp claw/claw/it_index.hpp
--- a/claw/it_index.hpp
+++ b/claw/it_index.hpp
@@ -143,7 +143,7 @@
     it_index<T> operator++(int) 
     {
       it_index<T> r(*this);
-      ++(this);
+      ++(*this);
       return r;
     }
 
@@ -159,7 +159,7 @@
     it_index<T> operator--(int) 
     {
       it_index<T> r(*this);
-      --(this);
+      --(*this);
       return r;
     }