diff --git a/exercises/03/vslc/include/vslc.h b/exercises/03/vslc/include/vslc.h
index 33744cd..4f5e541 100644
--- a/exercises/03/vslc/include/vslc.h
+++ b/exercises/03/vslc/include/vslc.h
@@ -23,6 +23,7 @@ int yyerror ( const char *error );
 /* These are defined in the parser generated by bison */
 extern int yylineno;
 extern int yylex ( void );
+extern int yylex_destroy( void );
 extern char yytext[];
 
 /* Global state */