diff --git a/hw/xquartz/mach-startup/bundle-main.c b/hw/xquartz/mach-startup/bundle-main.c
index 7531a0ead..e887c469d 100644
--- a/hw/xquartz/mach-startup/bundle-main.c
+++ b/hw/xquartz/mach-startup/bundle-main.c
@@ -449,7 +449,7 @@ static void ensure_path(const char *dir) {
     }
 }
 
-static void setup_env() {
+static void setup_env(void) {
     char *temp;
     const char *pds = NULL;
     const char *disp = getenv("DISPLAY");