https://bugs.gentoo.org/946659
--- a/src/optionlexer.h
+++ b/src/optionlexer.h
@@ -24,7 +24,7 @@
 #define OPTIONLEXER_H
 
 extern FILE *option_in;
-int option_parse();
+int option_parse(void *option_list);
 
 void option_lexer_init(char* filename);
 void option_lexer_deinit();