diff --git a/compat/mingw.c b/compat/mingw.c
index 44fa8866f7..8a2c905e6a 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1835,7 +1835,7 @@ pid_t waitpid(pid_t pid, int *status, int options)
 	return -1;
 }
 
-const char *get_windows_home_directory()
+const char *get_windows_home_directory(void)
 {
 	static const char *home_directory = NULL;
 	struct strbuf buf = STRBUF_INIT;