diff --git a/complete.cpp b/complete.cpp
index 78282cc7a..c7d12f815 100644
--- a/complete.cpp
+++ b/complete.cpp
@@ -1556,8 +1556,9 @@ static int try_complete_user( const wchar_t *cmd,
 void complete( const wchar_t *cmd,
 			   std::vector<completion_t> &comp )
 {
+
 	const wchar_t *tok_begin, *tok_end, *cmdsubst_begin, *cmdsubst_end, *prev_begin, *prev_end;
-	wchar_t *buff;
+	wcstring buff;
 	tokenizer tok;
 	const wchar_t *current_token=0, *current_command=0, *prev_token=0;
 	int on_command=0;
@@ -1601,10 +1602,7 @@ void complete( const wchar_t *cmd,
 	{
 		pos = cursor_pos-(cmdsubst_begin-cmd);
 		
-		buff = wcsndup( cmdsubst_begin, cmdsubst_end-cmdsubst_begin );
-		
-		if( !buff )
-			done=1;
+		buff = wcstring( cmdsubst_begin, cmdsubst_end-cmdsubst_begin );
 	}
 
 	if( !done )
@@ -1612,7 +1610,7 @@ void complete( const wchar_t *cmd,
 		int had_cmd=0;
 		int end_loop=0;
 
-		tok_init( &tok, buff, TOK_ACCEPT_UNFINISHED );
+		tok_init( &tok, buff.c_str(), TOK_ACCEPT_UNFINISHED );
 
 		while( tok_has_next( &tok) && !end_loop )
 		{
@@ -1623,21 +1621,21 @@ void complete( const wchar_t *cmd,
 				case TOK_STRING:
 				{
 
-					wchar_t *ncmd = tok_last( &tok );
-					int is_ddash = (wcscmp( ncmd, L"--" ) == 0) && ( (tok_get_pos( &tok )+2) < pos );
+					const wcstring ncmd = tok_last( &tok );
+					int is_ddash = (ncmd == L"--") && ( (tok_get_pos( &tok )+2) < pos );
 					
 					if( !had_cmd )
 					{
 
 						if( parser_keywords_is_subcommand( ncmd ) )
 						{
-							if( wcscmp( ncmd, L"builtin" )==0)
+							if (ncmd == L"builtin" )
 							{
 								use_function = 0;
 								use_command  = 0;
 								use_builtin  = 1;
 							}
-							else if( wcscmp( ncmd, L"command" )==0)
+							else if (ncmd == L"command")
 							{
 								use_command  = 1;
 								use_function = 0;
@@ -1653,9 +1651,9 @@ void complete( const wchar_t *cmd,
 							int token_end;
 							
 							free( (void *)current_command );
-							current_command = wcsdup( ncmd );
+							current_command = wcsdup( ncmd.c_str() );
 							
-							token_end = tok_get_pos( &tok ) + wcslen( ncmd );
+							token_end = tok_get_pos( &tok ) + ncmd.size();
 							
 							on_command = (pos <= token_end );
 							had_cmd=1;
@@ -1703,7 +1701,6 @@ void complete( const wchar_t *cmd,
 		}
 
 		tok_destroy( &tok );
-		free( buff );
 
 		/*
 		  Get the string to complete
diff --git a/parser.cpp b/parser.cpp
index 5a287e7cd..1349c6d17 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -1054,9 +1054,9 @@ const wchar_t *parser_t::current_line()
 	int lineno=1;
 
 	const wchar_t *file;
-	wchar_t *whole_str;
-	wchar_t *line;
-	wchar_t *line_end;
+	const wchar_t *whole_str;
+	const wchar_t *line;
+	const wchar_t *line_end;
 	int i;
 	int offset;
 	int current_line_width;
@@ -1158,7 +1158,7 @@ const wchar_t *parser_t::current_line()
 		}
 	}
 
-	free( line );
+	free( (void *)line );
 	parser_t::stack_trace( current_block, lineinfo );
 
 	return lineinfo.c_str();
@@ -1653,7 +1653,7 @@ int parser_t::parse_job( process_t *p,
 
 			case TOK_PIPE:
 			{
-				wchar_t *str = tok_string( tok );
+				const wchar_t *str = tok_string( tok );
 				if( tok_get_pos(tok)>0 && str[tok_get_pos(tok)-1] == L'|' )
 				{
 					error( SYNTAX_ERROR,
@@ -2333,7 +2333,7 @@ void parser_t::eval_job( tokenizer *tok )
 
 		case TOK_BACKGROUND:
 		{
-			wchar_t *str = tok_string( tok );
+			const wchar_t *str = tok_string( tok );
 			if( tok_get_pos(tok)>0 && str[tok_get_pos(tok)-1] == L'&' )
 			{
 				error( SYNTAX_ERROR,
diff --git a/tokenizer.cpp b/tokenizer.cpp
index 7ea5491fa..f02f47e04 100644
--- a/tokenizer.cpp
+++ b/tokenizer.cpp
@@ -144,7 +144,7 @@ void tok_init( tokenizer *tok, const wchar_t *b, int flags )
 	tok->has_next=1;
 
 	tok->has_next = (*b != L'\0');
-	tok->orig_buff = tok->buff = (wchar_t *)(b);
+	tok->orig_buff = tok->buff = b;
 	tok_next( tok );
 }
 
@@ -154,7 +154,7 @@ void tok_destroy( tokenizer *tok )
 	
 	free( tok->last );
 	if( tok->free_orig )
-		free( tok->orig_buff );
+		free( (void *)tok->orig_buff );
 }
 
 int tok_last_type( tokenizer *tok )
@@ -624,7 +624,7 @@ void tok_next( tokenizer *tok )
 		{
 			if( iswdigit( *tok->buff ) )
 			{
-				wchar_t *orig = tok->buff;
+				const wchar_t *orig = tok->buff;
 				int fd = 0;
 				while( iswdigit( *tok->buff ) )
 					fd = (fd*10) + (*(tok->buff++) - L'0');
@@ -646,7 +646,7 @@ void tok_next( tokenizer *tok )
 
 }
 
-wchar_t *tok_string( tokenizer *tok )
+const wchar_t *tok_string( tokenizer *tok )
 {
 	return tok?tok->orig_buff:0;
 }
diff --git a/tokenizer.h b/tokenizer.h
index 731f49bf0..ff7c38e90 100644
--- a/tokenizer.h
+++ b/tokenizer.h
@@ -68,9 +68,9 @@ enum tokenizer_error
 struct tokenizer
 {
 	/** A pointer into the original string, showing where the next token begins */
-	wchar_t *buff;
+	const wchar_t *buff;
 	/** A copy of the original string */
-	wchar_t *orig_buff;
+	const wchar_t *orig_buff;
 	/** A pointer to the last token*/
 	wchar_t *last;
 	
@@ -150,7 +150,7 @@ void tok_destroy( tokenizer *tok );
 /**
    Returns the original string to tokenizer
  */
-wchar_t *tok_string( tokenizer *tok );
+const wchar_t *tok_string( tokenizer *tok );
 
 
 /**