diff --git a/makefile b/makefile
index db65cfe..cd7109b 100644
--- a/makefile
+++ b/makefile
@@ -1,4 +1,4 @@
-CFLAGS = -std=c23 -Wextra -pedantic -Wall -O0 -g3 -fsanitize=address
+CFLAGS = -std=c11 -Wextra -pedantic -Wall -O0 -g3 -fsanitize=address
 LDFLAGS = -lncurses -fsanitize=address
 
 spel: box.o main.o ui.o util.o chart.o
diff --git a/ui.c b/ui.c
index a099639..986c2b2 100644
--- a/ui.c
+++ b/ui.c
@@ -30,7 +30,7 @@ ui_init(void)
     refresh();
 }
 
-void ui_end()
+void ui_end(void)
 {
     endwin();
 }