commit b111a86e65d630a6d5263bfe865f0aabb349ef87
Author: Oscar Lesta <oscar.lesta@gmail.com>
Date:   Tue Apr 1 23:04:04 2025 -0300

    Fix compilation in Haiku.

diff --git a/fnc.bld.mk b/fnc.bld.mk
index b9d5fa4..16a0175 100644
--- a/fnc.bld.mk
+++ b/fnc.bld.mk
@@ -40,14 +40,26 @@ SQLITE_CFLAGS =	${CFLAGS} \
 # FLAGS NEEDED TO BUILD LIBFOSSIL
 FOSSIL_CFLAGS =	${CFLAGS}
 
+UNAME_S := $(shell uname -s)
+
 # On SOME Linux (e.g., Ubuntu 18.04.6), we have to include wchar curses from
 # I/.../ncursesw, but linking to -lncursesw (w/ no special -L path) works fine.
 # FLAGS NEEDED TO BUILD FNC
+ifeq ($(UNAME_S),Haiku)
+FNC_CFLAGS =	${CFLAGS} -Wstrict-prototypes -Wmissing-prototypes -fPIC \
+		-Wunused-variable -I./lib -I./include -I$(shell finddir B_SYSTEM_HEADERS_DIRECTORY) \
+		-DFNC_VERSION=${VERSION} -DFNC_HASH=${HASH} -DFNC_DATE="${DATE}"
+else
 FNC_CFLAGS =	${CFLAGS} -Wstrict-prototypes -Wmissing-prototypes -fPIC \
 		-Wunused-variable -I./lib -I./include -I/usr/include/ncursesw \
 		-DFNC_VERSION=${VERSION} -DFNC_HASH=${HASH} -DFNC_DATE="${DATE}"
+endif
 
+ifeq ($(UNAME_S),Haiku)
+FNC_LDFLAGS =	${LDFLAGS} -lbsd -lz
+else
 FNC_LDFLAGS =	${LDFLAGS} -lm -lutil -lz -lpthread
+endif
 
 # Compile-time checks and runtime protection mechanisms from the compiler
 # hardening document: https://best.openssf.org/Compiler-Hardening-Guides
diff --git a/include/fnc_compat.h b/include/fnc_compat.h
index be51465..03959b0 100644
--- a/include/fnc_compat.h
+++ b/include/fnc_compat.h
@@ -52,7 +52,7 @@
 #define _OPENBSD_SOURCE		/* strtonum(3) */
 #endif
 
-#if !defined(__linux__) && !defined(__APPLE__)
+#if !defined(__linux__) && !defined(__APPLE__) && !defined(__HAIKU__)
 #define HAVE_REALLOCARRAY
 #define HAVE_BSD_STRING
 #define HAVE_STRTONUM
@@ -76,6 +76,12 @@
 #endif  /* __MAC_OS_X_VERSION_MAX_ALLOWED */
 #endif  /* __APPLE__ */
 
+#if defined(__HAIKU__)
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
+#endif  /* ___HAIKU__ */
+
 #ifndef __predict_true
 #ifdef __has_builtin
 #if __has_builtin(__builtin_expect)
diff --git a/src/fnc.c b/src/fnc.c
index 5871494..569a71a 100644
--- a/src/fnc.c
+++ b/src/fnc.c
@@ -1007,7 +1007,7 @@ main(int argc, char **argv)
 
 	argc -= optind;
 	argv += optind;
-#ifdef __linux__
+#if defined(__linux__) || defined(__HAIKU__)
 	optind = 0;
 #else
 	optind = 1;