diff --git a/include/mgba-util/platform/windows/getopt.h b/include/mgba-util/platform/windows/getopt.h
index 5ea2dbe6f..22a196ef6 100644
--- a/include/mgba-util/platform/windows/getopt.h
+++ b/include/mgba-util/platform/windows/getopt.h
@@ -27,6 +27,8 @@
 extern "C" {
 #endif
 
+struct option;
+
 #define	REPLACE_GETOPT		/* use this getopt as the system getopt(3) */
 
 #ifdef REPLACE_GETOPT