diff --git a/parser.c b/parser.c
index 1c13cfc13..2c8789fef 100644
--- a/parser.c
+++ b/parser.c
@@ -470,7 +470,7 @@ int parser_is_subcommand( const wchar_t *cmd )
    Test if the specified string is command that opens a new block
 */
 
-static int parser_is_block( wchar_t *word)
+static int parser_is_block( const wchar_t *word)
 {
 	return contains_str( word,
 						 L"for",
@@ -482,7 +482,7 @@ static int parser_is_block( wchar_t *word)
 						 (void *)0 );
 }
 
-int parser_is_reserved( wchar_t *word)
+int parser_is_reserved( const wchar_t *word)
 {
 	return parser_is_block(word) ||
 		parser_is_subcommand( word ) ||
diff --git a/parser.h b/parser.h
index 51c5b7150..3542b8f07 100644
--- a/parser.h
+++ b/parser.h
@@ -257,7 +257,7 @@ int parser_is_subcommand( const wchar_t *cmd );
    \param word The command name to test
    \return 1 of the command parameter is a command, 0 otherwise
 */
-int parser_is_reserved( wchar_t *word );
+int parser_is_reserved( const wchar_t *word );
 
 /**
    Returns a string describing the current parser pisition in the format 'FILENAME (line LINE_NUMBER): LINE'.