diff --git a/builtin.cpp b/builtin.cpp
index 4af4f208e..d7ba8a11a 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -2128,10 +2128,9 @@ static int builtin_read( parser_t &parser, wchar_t **argv )
 	}
 	else
 	{
-		string_buffer_t sb;
 		int eof=0;
 		
-		sb_init( &sb );
+		wcstring sb;
 		
 		while( 1 )
 		{
@@ -2178,17 +2177,16 @@ static int builtin_read( parser_t &parser, wchar_t **argv )
 
 			if( res == L'\n' )
 				break;
-
-			sb_append_char( &sb, res );
+    
+            sb.push_back(res);
 		}
 
-		if( sb.used < 2 && eof )
+		if( sb.size() < 2 && eof )
 		{
 			exit_res = 1;
 		}
 		
-		buff = wcsdup( (wchar_t *)sb.buff );
-		sb_destroy( &sb );
+		buff = wcsdup( sb.c_str() );
 	}
 
 	if( i != argc && !exit_res )
diff --git a/builtin_commandline.cpp b/builtin_commandline.cpp
index d470a3913..26b40e624 100644
--- a/builtin_commandline.cpp
+++ b/builtin_commandline.cpp
@@ -94,42 +94,40 @@ static void replace_part( const wchar_t *begin,
 						  int append_mode )
 {
 	const wchar_t *buff = get_buffer();
-	string_buffer_t out;
 	int out_pos=get_cursor_pos();
-					
-	sb_init( &out );
+    
+    wcstring out;
 
-	sb_append_substring( &out, buff, begin-buff );
+    out.append(buff, begin - buff);
 					
 	switch( append_mode)
 	{
 		case REPLACE_MODE:
 		{
 							
-			sb_append( &out, insert );
+			out.append(insert);
 			out_pos = wcslen( insert ) + (begin-buff);							
 			break;
 							
 		}
 		case APPEND_MODE:
 		{
-			sb_append_substring( &out, begin, end-begin );
-			sb_append( &out, insert );
+			out.append( begin, end-begin );
+			out.append( insert );
 			break;
 		}
 		case INSERT_MODE:
 		{
 			int cursor = get_cursor_pos() -(begin-buff);
-			sb_append_substring( &out, begin, cursor );
-			sb_append( &out, insert );
-			sb_append_substring( &out, begin+cursor, end-begin-cursor );
+			out.append( begin, cursor );
+			out.append( insert );
+			out.append( begin+cursor, end-begin-cursor );
 			out_pos +=  wcslen( insert );							
 			break;
 		}
 	}
-	sb_append( &out, end );
-	reader_set_buffer( (wchar_t *)out.buff, out_pos );
-	sb_destroy( &out );
+	out.append( end );
+	reader_set_buffer( out, out_pos );
 }
 	
 /**
diff --git a/fish.cpp b/fish.cpp
index 3b8f92f8f..29c1ccf42 100644
--- a/fish.cpp
+++ b/fish.cpp
@@ -324,7 +324,6 @@ int main( int argc, char **argv )
 				char **ptr; 
 				char *file = *(argv+(my_optind++));
 				int i; 
-				string_buffer_t sb;
 				int fd;
 				wchar_t *rel_filename, *abs_filename;
 								
@@ -336,19 +335,15 @@ int main( int argc, char **argv )
 
 				if( *(argv+my_optind))
 				{
-					sb_init( &sb );
-				
+                    wcstring sb;
 					for( i=1,ptr = argv+my_optind; *ptr; i++, ptr++ )
 					{
 						if( i != 1 )
-							sb_append( &sb, ARRAY_SEP_STR );
-						wchar_t *val = str2wcs( *ptr );
-						sb_append( &sb, val );
-						free( val );
+                            sb.append( ARRAY_SEP_STR );
+                        sb.append( str2wcstring( *ptr ));
 					}
 				
-					env_set( L"argv", (wchar_t *)sb.buff, 0 );
-					sb_destroy( &sb );
+					env_set( L"argv", sb.c_str(), 0 );
 				}
 
 				rel_filename = str2wcs( file );
diff --git a/reader.cpp b/reader.cpp
index bbf6b608f..139efbc2b 100644
--- a/reader.cpp
+++ b/reader.cpp
@@ -2108,15 +2108,14 @@ history_t *reader_get_history(void) {
 	return data ? data->history : NULL;
 }
 
-void reader_set_buffer( const wchar_t *b, int p )
+void reader_set_buffer( const wcstring &b, int p )
 {
 	if( !data )
 		return;
 
     /* Callers like to pass us pointers into ourselves, so be careful! I don't know if we can use operator= with a pointer to our interior, so use an intermediate. */
-	int l = wcslen( b );
-    const wcstring tmp = b;
-    data->command_line = tmp;
+	size_t l = b.size();
+    data->command_line = b;
     
     data->check_size();
 
diff --git a/reader.h b/reader.h
index 37da4d1ee..9cb412e89 100644
--- a/reader.h
+++ b/reader.h
@@ -95,7 +95,7 @@ history_t *reader_get_history(void);
    \param b the new buffer value
    \param p the cursor position. If \c p is less than zero, the cursor is placed on the last character.
 */
-void reader_set_buffer( const wchar_t *b, int p );
+void reader_set_buffer( const wcstring &b, int p );
 
 /**
    Get the current cursor position in the command line. If interactive