Remove -O3
Remove -Werror
Link with -lcurses to appease lld

Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -4,10 +4,10 @@ MANDIR = $(DESTDIR)$(PREFIX)/share/man/man1
 DOCDIR = $(DESTDIR)$(PREFIX)/share/doc/bcal
 STRIP ?= strip
 
-CFLAGS_OPTIMIZATION ?= -O3
-CFLAGS_WARNINGS     ?= -Wall -Wextra -Wno-unused-parameter -Werror
+CFLAGS_OPTIMIZATION ?=
+CFLAGS_WARNINGS     ?= -Wall -Wextra -Wno-unused-parameter
 
-LDLIBS_READLINE ?= -lreadline
+LDLIBS_READLINE ?= -lreadline -lcurses
 
 CFLAGS += $(CFLAGS_OPTIMIZATION) $(CFLAGS_WARNINGS)
 LDLIBS += $(LDLIBS_READLINE)