diff --git a/data/bin/install-wifi-firmwares.sh b/data/bin/install-wifi-firmwares.sh
index 2b29732c8e..ca75b2ad73 100755
--- a/data/bin/install-wifi-firmwares.sh
+++ b/data/bin/install-wifi-firmwares.sh
@@ -276,7 +276,7 @@ function BuildBroadcomFWCutter()
 
 	# Build b43-fwcutter.
 	echo "Compiling b43-fwcutter for installing Broadcom's firmware ..."
-	make PREFIX=/boot/system CFLAGS="-I. -Wall -D_BSD_SOURCE" >/dev/null 2>&1
+	make PREFIX=/boot/system CFLAGS="-I. -Wall" >/dev/null 2>&1
 	result=$?
 	if [ $result -gt 0 ]; then
 		echo "... failed to compile b43-fwcutter."
diff --git a/headers/compatibility/bsd/arpa/ftp.h b/headers/compatibility/bsd/arpa/ftp.h
index 38f9772ba2..b621e9fd3e 100644
--- a/headers/compatibility/bsd/arpa/ftp.h
+++ b/headers/compatibility/bsd/arpa/ftp.h
@@ -37,7 +37,10 @@
 #define	_ARPA_FTP_H_
 
 
-#ifdef _BSD_SOURCE
+#include <features.h>
+
+
+#ifdef _DEFAULT_SOURCE
 
 
 /* Definitions for FTP; see RFC-765. */
diff --git a/headers/compatibility/bsd/arpa/telnet.h b/headers/compatibility/bsd/arpa/telnet.h
index 3055a551f8..dfa1525d6a 100644
--- a/headers/compatibility/bsd/arpa/telnet.h
+++ b/headers/compatibility/bsd/arpa/telnet.h
@@ -38,7 +38,10 @@
 #define	_ARPA_TELNET_H_
 
 
-#ifdef _BSD_SOURCE
+#include <features.h>
+
+
+#ifdef _DEFAULT_SOURCE
 
 
 /*
diff --git a/headers/compatibility/bsd/arpa/tftp.h b/headers/compatibility/bsd/arpa/tftp.h
index 10880f3f8d..3413b2e844 100644
--- a/headers/compatibility/bsd/arpa/tftp.h
+++ b/headers/compatibility/bsd/arpa/tftp.h
@@ -38,7 +38,10 @@
 #define	_ARPA_TFTP_H_
 
 
-#ifdef _BSD_SOURCE
+#include <features.h>
+
+
+#ifdef _DEFAULT_SOURCE
 
 
 /*
diff --git a/headers/compatibility/bsd/endian.h b/headers/compatibility/bsd/endian.h
index 44381cedfc..0dcf5ee10a 100644
--- a/headers/compatibility/bsd/endian.h
+++ b/headers/compatibility/bsd/endian.h
@@ -7,9 +7,10 @@
 
 
 #include_next <endian.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 #include <config/HaikuConfig.h>
 #include <support/ByteOrder.h>
diff --git a/headers/compatibility/bsd/err.h b/headers/compatibility/bsd/err.h
index 8396c680dd..64a086c26c 100644
--- a/headers/compatibility/bsd/err.h
+++ b/headers/compatibility/bsd/err.h
@@ -37,8 +37,9 @@
 #ifndef _ERR_H_
 #define	_ERR_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 /*
diff --git a/headers/compatibility/bsd/errno.h b/headers/compatibility/bsd/errno.h
index 3ae5026680..d3398c3f3d 100644
--- a/headers/compatibility/bsd/errno.h
+++ b/headers/compatibility/bsd/errno.h
@@ -7,9 +7,10 @@
 
 
 #include_next <errno.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #define EDOOFUS	EINVAL
diff --git a/headers/compatibility/bsd/features.h b/headers/compatibility/bsd/features.h
new file mode 100644
index 0000000000..4513b500e4
--- /dev/null
+++ b/headers/compatibility/bsd/features.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright 2019 Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _FEATURES_H
+#define _FEATURES_H
+
+
+#if defined(_BSD_SOURCE) \
+	|| (!defined(__STRICT_ANSI__) && !defined(_POSIX_C_SOURCE))
+	#define _DEFAULT_SOURCE
+#endif
+
+
+#endif // _FEATURES_H
diff --git a/headers/compatibility/bsd/ifaddrs.h b/headers/compatibility/bsd/ifaddrs.h
index 2716a709f6..44a14035a2 100644
--- a/headers/compatibility/bsd/ifaddrs.h
+++ b/headers/compatibility/bsd/ifaddrs.h
@@ -5,8 +5,9 @@
 #ifndef _IFADDRS_H
 #define _IFADDRS_H
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/libutil.h b/headers/compatibility/bsd/libutil.h
index 2add799326..1fc36684a2 100644
--- a/headers/compatibility/bsd/libutil.h
+++ b/headers/compatibility/bsd/libutil.h
@@ -39,8 +39,9 @@
 #ifndef _LIBUTIL_H_
 #define	_LIBUTIL_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <stdint.h>
diff --git a/headers/compatibility/bsd/netinet/in_systm.h b/headers/compatibility/bsd/netinet/in_systm.h
index 41d68f43f7..6d19ab0351 100644
--- a/headers/compatibility/bsd/netinet/in_systm.h
+++ b/headers/compatibility/bsd/netinet/in_systm.h
@@ -6,7 +6,10 @@
 #define _NETINET_IN_SYSTM_H_
 
 
-#ifdef _BSD_SOURCE
+#include <features.h>
+
+
+#ifdef _DEFAULT_SOURCE
 
 
 #include <stdint.h>
diff --git a/headers/compatibility/bsd/paths.h b/headers/compatibility/bsd/paths.h
index dc62490e7f..e77457e80b 100644
--- a/headers/compatibility/bsd/paths.h
+++ b/headers/compatibility/bsd/paths.h
@@ -37,8 +37,9 @@
 #ifndef _PATHS_H_
 #define	_PATHS_H_
 
+#include <features.h>
 
-#if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
+#if defined(_DEFAULT_SOURCE) || defined(_GNU_SOURCE)
 
 
 #include <sys/cdefs.h>
@@ -141,7 +142,7 @@ __END_DECLS
 #endif /* RESCUE */
 
 
-#endif /* _BSD_SOURCE || _GNU_SOURCE */
+#endif /* _DEFAULT_SOURCE || _GNU_SOURCE */
 
 
 #endif /* !_PATHS_H_ */
diff --git a/headers/compatibility/bsd/pty.h b/headers/compatibility/bsd/pty.h
index 3ccf7f87bf..1bfdc851f6 100644
--- a/headers/compatibility/bsd/pty.h
+++ b/headers/compatibility/bsd/pty.h
@@ -5,8 +5,9 @@
 #ifndef _BSD_PTY_H_
 #define _BSD_PTY_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <sys/cdefs.h>
diff --git a/headers/compatibility/bsd/readpassphrase.h b/headers/compatibility/bsd/readpassphrase.h
index 23ac37db40..d89dcb6576 100644
--- a/headers/compatibility/bsd/readpassphrase.h
+++ b/headers/compatibility/bsd/readpassphrase.h
@@ -23,7 +23,9 @@
 #ifndef _READPASSPHRASE_H_
 #define _READPASSPHRASE_H_
 
-#ifdef _BSD_SOURCE
+#include <features.h>
+
+#ifdef _DEFAULT_SOURCE
 
 #define RPP_ECHO_OFF    0x00		/* Turn off echo (default). */
 #define RPP_ECHO_ON     0x01		/* Leave echo on. */
diff --git a/headers/compatibility/bsd/signal.h b/headers/compatibility/bsd/signal.h
index 58f16bb7cc..f4bfc92b21 100644
--- a/headers/compatibility/bsd/signal.h
+++ b/headers/compatibility/bsd/signal.h
@@ -7,9 +7,10 @@
 
 
 #include_next <signal.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #define	sigmask(sig) (1 << ((sig) - 1))
diff --git a/headers/compatibility/bsd/stdio.h b/headers/compatibility/bsd/stdio.h
index 5f80fc087c..b73d0905fe 100644
--- a/headers/compatibility/bsd/stdio.h
+++ b/headers/compatibility/bsd/stdio.h
@@ -7,9 +7,10 @@
 
 
 #include_next <stdio.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/stdlib.h b/headers/compatibility/bsd/stdlib.h
index 6b9e0b726d..3f7023b668 100644
--- a/headers/compatibility/bsd/stdlib.h
+++ b/headers/compatibility/bsd/stdlib.h
@@ -7,9 +7,10 @@
 
 
 #include_next <stdlib.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/string.h b/headers/compatibility/bsd/string.h
index c19ea27f87..45756b0bec 100644
--- a/headers/compatibility/bsd/string.h
+++ b/headers/compatibility/bsd/string.h
@@ -7,9 +7,10 @@
 
 
 #include_next <string.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/stringlist.h b/headers/compatibility/bsd/stringlist.h
index ee1cf13be7..65be681b76 100644
--- a/headers/compatibility/bsd/stringlist.h
+++ b/headers/compatibility/bsd/stringlist.h
@@ -36,8 +36,9 @@
 #ifndef _STRINGLIST_H
 #define _STRINGLIST_H 
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <sys/cdefs.h>
diff --git a/headers/compatibility/bsd/sys/cdefs.h b/headers/compatibility/bsd/sys/cdefs.h
index 6647d2e90e..6d22755b17 100644
--- a/headers/compatibility/bsd/sys/cdefs.h
+++ b/headers/compatibility/bsd/sys/cdefs.h
@@ -7,9 +7,10 @@
 
 
 #include_next <sys/cdefs.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #define __FBSDID(x)
diff --git a/headers/compatibility/bsd/sys/ioccom.h b/headers/compatibility/bsd/sys/ioccom.h
index ea9583cad4..52b86a00cd 100644
--- a/headers/compatibility/bsd/sys/ioccom.h
+++ b/headers/compatibility/bsd/sys/ioccom.h
@@ -6,8 +6,9 @@
 #ifndef _SYS_IOCCOM_H
 #define _SYS_IOCCOM_H
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 /**
diff --git a/headers/compatibility/bsd/sys/link_elf.h b/headers/compatibility/bsd/sys/link_elf.h
index 03e4a6ca9d..6dc120e199 100644
--- a/headers/compatibility/bsd/sys/link_elf.h
+++ b/headers/compatibility/bsd/sys/link_elf.h
@@ -44,7 +44,7 @@
 #define	_SYS_LINK_ELF_H_
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <os/kernel/elf.h>
diff --git a/headers/compatibility/bsd/sys/md4.h b/headers/compatibility/bsd/sys/md4.h
index 07992e9cea..9f7338372a 100644
--- a/headers/compatibility/bsd/sys/md4.h
+++ b/headers/compatibility/bsd/sys/md4.h
@@ -27,8 +27,9 @@
 #ifndef _MD4_H_
 #define _MD4_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 /* MD4 context. */
diff --git a/headers/compatibility/bsd/sys/md5.h b/headers/compatibility/bsd/sys/md5.h
index 6f077b4f32..ecc7ce0579 100644
--- a/headers/compatibility/bsd/sys/md5.h
+++ b/headers/compatibility/bsd/sys/md5.h
@@ -28,8 +28,9 @@ documentation and/or software.
 #ifndef _SYS_MD5_H_
 #define _SYS_MD5_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <stdint.h>
diff --git a/headers/compatibility/bsd/sys/param.h b/headers/compatibility/bsd/sys/param.h
index f0001fa155..3e23785db1 100644
--- a/headers/compatibility/bsd/sys/param.h
+++ b/headers/compatibility/bsd/sys/param.h
@@ -7,9 +7,10 @@
 
 
 #include_next <sys/param.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifndef _ALIGNBYTES
diff --git a/headers/compatibility/bsd/sys/queue.h b/headers/compatibility/bsd/sys/queue.h
index e5841306ac..c5733cfa75 100644
--- a/headers/compatibility/bsd/sys/queue.h
+++ b/headers/compatibility/bsd/sys/queue.h
@@ -33,8 +33,9 @@
 #ifndef _SYS_QUEUE_H_
 #define	_SYS_QUEUE_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <sys/cdefs.h>
@@ -619,6 +620,6 @@ void	remque(void *a);
 
 #endif /* _KERNEL */
 
-#endif /* _BSD_SOURCE */
+#endif /* _DEFAULT_SOURCE */
 
 #endif /* !_SYS_QUEUE_H_ */
diff --git a/headers/compatibility/bsd/sys/time.h b/headers/compatibility/bsd/sys/time.h
index 6e71a66813..ff671e0a37 100644
--- a/headers/compatibility/bsd/sys/time.h
+++ b/headers/compatibility/bsd/sys/time.h
@@ -7,9 +7,10 @@
 
 
 #include_next <sys/time.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/sys/wait.h b/headers/compatibility/bsd/sys/wait.h
index 567f2b3d6d..5d24e3a410 100644
--- a/headers/compatibility/bsd/sys/wait.h
+++ b/headers/compatibility/bsd/sys/wait.h
@@ -7,9 +7,10 @@
 
 
 #include_next <sys/wait.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <sys/resource.h>
diff --git a/headers/compatibility/bsd/time.h b/headers/compatibility/bsd/time.h
index ff0fb0ec7b..cc8c324213 100644
--- a/headers/compatibility/bsd/time.h
+++ b/headers/compatibility/bsd/time.h
@@ -7,9 +7,10 @@
 
 
 #include_next <time.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #ifdef __cplusplus
diff --git a/headers/compatibility/bsd/unistd.h b/headers/compatibility/bsd/unistd.h
index fbcd17cce1..5bc3045954 100644
--- a/headers/compatibility/bsd/unistd.h
+++ b/headers/compatibility/bsd/unistd.h
@@ -7,9 +7,10 @@
 
 
 #include_next <unistd.h>
+#include <features.h>
 
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #define L_SET	SEEK_SET
diff --git a/headers/compatibility/bsd/vis.h b/headers/compatibility/bsd/vis.h
index d9d37281e6..932e59ee54 100644
--- a/headers/compatibility/bsd/vis.h
+++ b/headers/compatibility/bsd/vis.h
@@ -35,8 +35,9 @@
 #ifndef _VIS_H_
 #define	_VIS_H_
 
+#include <features.h>
 
-#ifdef _BSD_SOURCE
+#ifdef _DEFAULT_SOURCE
 
 
 #include <sys/types.h>
diff --git a/src/add-ons/kernel/bus_managers/firewire/Jamfile b/src/add-ons/kernel/bus_managers/firewire/Jamfile
index 7151a9f36f..74939f4487 100644
--- a/src/add-ons/kernel/bus_managers/firewire/Jamfile
+++ b/src/add-ons/kernel/bus_managers/firewire/Jamfile
@@ -4,7 +4,7 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UsePrivateHeaders firewire ;
 UsePrivateKernelHeaders ;
 
-local defines = [ FDefines _KERNEL=1 _BSD_SOURCE=1 ] ;
+local defines = [ FDefines _KERNEL=1 ] ;
 SubDirCcFlags $(defines) ;
 SubDirC++Flags $(defines) ;
 
diff --git a/src/add-ons/kernel/drivers/bus/firewire/Jamfile b/src/add-ons/kernel/drivers/bus/firewire/Jamfile
index fd456f583d..f9ed678999 100644
--- a/src/add-ons/kernel/drivers/bus/firewire/Jamfile
+++ b/src/add-ons/kernel/drivers/bus/firewire/Jamfile
@@ -4,7 +4,7 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UsePrivateHeaders firewire ;
 UsePrivateKernelHeaders ;
 
-SubDirCcFlags [ FDefines _KERNEL=1 _BSD_SOURCE=1 ] ;
+SubDirCcFlags [ FDefines _KERNEL=1 ] ;
 
 KernelAddon fw_raw :
 	fw_raw.c
diff --git a/src/add-ons/kernel/drivers/disk/nvme/Jamfile b/src/add-ons/kernel/drivers/disk/nvme/Jamfile
index 48286fb81d..081745c76b 100644
--- a/src/add-ons/kernel/drivers/disk/nvme/Jamfile
+++ b/src/add-ons/kernel/drivers/disk/nvme/Jamfile
@@ -2,6 +2,7 @@ SubDir HAIKU_TOP src add-ons kernel drivers disk nvme ;
 
 UsePrivateKernelHeaders ;
 SubDirHdrs $(HAIKU_TOP) src system kernel device_manager ;
+SubDirSysHdrs $(HAIKU_TOP) headers compatibility bsd ;
 
 UseHeaders [ FDirName $(SUBDIR) ] : true ;
 
diff --git a/src/add-ons/kernel/drivers/disk/nvme/libnvme/nvme_common.h b/src/add-ons/kernel/drivers/disk/nvme/libnvme/nvme_common.h
index d039dfa821..2b3f549bf3 100644
--- a/src/add-ons/kernel/drivers/disk/nvme/libnvme/nvme_common.h
+++ b/src/add-ons/kernel/drivers/disk/nvme/libnvme/nvme_common.h
@@ -52,11 +52,8 @@
 #include <time.h>
 #include <sys/types.h>
 #include <sys/cdefs.h>
-#ifdef __HAIKU__
-#define _BSD_SOURCE
-#include <compatibility/bsd/sys/queue.h>
-#else
 #include <sys/queue.h>
+#ifndef __HAIKU__
 #include <linux/types.h>
 #endif
 
diff --git a/src/add-ons/kernel/file_systems/userlandfs/server/beos/fs_cache.c b/src/add-ons/kernel/file_systems/userlandfs/server/beos/fs_cache.c
index 016c0bf1af..d01c258012 100644
--- a/src/add-ons/kernel/file_systems/userlandfs/server/beos/fs_cache.c
+++ b/src/add-ons/kernel/file_systems/userlandfs/server/beos/fs_cache.c
@@ -36,8 +36,6 @@
    dbg@be.com
 */
 
-#define _BSD_SOURCE
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <memory.h>
diff --git a/src/add-ons/media/media-add-ons/firewire_dv/Jamfile b/src/add-ons/media/media-add-ons/firewire_dv/Jamfile
index 5fcba34523..8695fa29ea 100644
--- a/src/add-ons/media/media-add-ons/firewire_dv/Jamfile
+++ b/src/add-ons/media/media-add-ons/firewire_dv/Jamfile
@@ -5,7 +5,6 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UsePrivateHeaders firewire ;
 UsePrivateHeaders media ;
 UsePrivateHeaders shared ;
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
 
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
diff --git a/src/apps/debugger/Jamfile b/src/apps/debugger/Jamfile
index e8f66fc6ae..5baf313679 100644
--- a/src/apps/debugger/Jamfile
+++ b/src/apps/debugger/Jamfile
@@ -32,8 +32,6 @@ UseBuildFeatureHeaders libedit ;
 
 LINKFLAGS += -Wl,--exclude-libs,ALL ;
 
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 SEARCH_SOURCE += [ FDirName $(SUBDIR) settings ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) user_interface cli ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) user_interface cli commands ] ;
diff --git a/src/bin/fwcontrol/Jamfile b/src/bin/fwcontrol/Jamfile
index 9cf8bda467..3c133212ab 100644
--- a/src/bin/fwcontrol/Jamfile
+++ b/src/bin/fwcontrol/Jamfile
@@ -2,7 +2,6 @@ SubDir HAIKU_TOP src bin fwcontrol ;
 
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UsePrivateHeaders firewire ;
-SubDirCcFlags [ FDefines _BSD_SOURCE=1 ] ;
 
 BinCommand fwcontrol :
 	eui64.c
diff --git a/src/bin/multiuser/Jamfile b/src/bin/multiuser/Jamfile
index 13306c51de..14cebb65b6 100644
--- a/src/bin/multiuser/Jamfile
+++ b/src/bin/multiuser/Jamfile
@@ -7,7 +7,6 @@ UsePrivateHeaders kernel ;
 UsePrivateHeaders libroot ;
 UsePrivateHeaders shared ;
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
 
 StaticLibrary libmultiuser_utils.a : multiuser_utils.cpp ;
 
diff --git a/src/bin/network/ftpd/Jamfile b/src/bin/network/ftpd/Jamfile
index 9908c9f9d2..bd94a9e6d6 100644
--- a/src/bin/network/ftpd/Jamfile
+++ b/src/bin/network/ftpd/Jamfile
@@ -2,7 +2,6 @@ SubDir HAIKU_TOP src bin network ftpd ;
 
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UseHeaders $(SUBDIR) : true ;
-SubDirCcFlags [ FDefines _BSD_SOURCE=1 ] ;
 
 BinCommand ftpd :
 	ftpd.c
diff --git a/src/bin/network/ifconfig/Jamfile b/src/bin/network/ifconfig/Jamfile
index 679d2906a6..64d6804229 100644
--- a/src/bin/network/ifconfig/Jamfile
+++ b/src/bin/network/ifconfig/Jamfile
@@ -5,8 +5,6 @@ UsePrivateHeaders net ;
 UseHeaders [ FDirName $(HAIKU_TOP) src libs compat ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) src libs compat freebsd_wlan ] : true ;
 
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 BinCommand ifconfig :
 	ifconfig.cpp
 	MediaTypes.cpp
diff --git a/src/bin/network/telnet/Jamfile b/src/bin/network/telnet/Jamfile
index d8fb20a6cf..c1a31fd514 100644
--- a/src/bin/network/telnet/Jamfile
+++ b/src/bin/network/telnet/Jamfile
@@ -6,7 +6,7 @@ UseHeaders [ FDirName $(HAIKU_TOP) src libs libtelnet ] : false ;
 
 UseBuildFeatureHeaders ncurses ;
 
-local defines = [ FDefines USE_TERMIO=1 OLD_ENVIRON=1 ENV_HACK=1 _BSD_SOURCE=1 ] ;
+local defines = [ FDefines USE_TERMIO=1 OLD_ENVIRON=1 ENV_HACK=1 ] ;
 
 SubDirCcFlags $(defines) ;
 SubDirC++Flags $(defines) ;
diff --git a/src/bin/network/telnetd/Jamfile b/src/bin/network/telnetd/Jamfile
index 1581c7d54f..2faf3facac 100644
--- a/src/bin/network/telnetd/Jamfile
+++ b/src/bin/network/telnetd/Jamfile
@@ -5,7 +5,7 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) src libs ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) src libs libtelnet ] : false ;
 
-local defines = [ FDefines USE_TERMIO=1 _BSD_SOURCE=1 ] ;
+local defines = [ FDefines USE_TERMIO=1 ] ;
 
 SubDirCcFlags $(defines) ;
 SubDirC++Flags $(defines) ;
diff --git a/src/kits/debugger/Jamfile b/src/kits/debugger/Jamfile
index eb7113ac43..aaa4e1fb55 100644
--- a/src/kits/debugger/Jamfile
+++ b/src/kits/debugger/Jamfile
@@ -34,8 +34,6 @@ UsePrivateSystemHeaders ;
 
 LINKFLAGS += -Wl,--exclude-libs,ALL ;
 
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 SEARCH_SOURCE += [ FDirName $(SUBDIR) arch ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) arch x86 ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) arch x86_64 ] ;
diff --git a/src/kits/network/libnetapi/Jamfile b/src/kits/network/libnetapi/Jamfile
index c94dc6f22a..75f5d821c1 100644
--- a/src/kits/network/libnetapi/Jamfile
+++ b/src/kits/network/libnetapi/Jamfile
@@ -8,8 +8,6 @@ UseHeaders [ FDirName $(HAIKU_TOP) src libs compat freebsd_wlan ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) headers os add-ons network_settings ]
 	: true ;
 
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
 	on $(architectureObject) {
diff --git a/src/libs/bsd/Jamfile b/src/libs/bsd/Jamfile
index f405a8ca13..3ec438e8c7 100644
--- a/src/libs/bsd/Jamfile
+++ b/src/libs/bsd/Jamfile
@@ -2,9 +2,6 @@ SubDir HAIKU_TOP src libs bsd ;
 
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 
-SubDirCcFlags [ FDefines _BSD_SOURCE=1 ] ;
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
 	on $(architectureObject) {
diff --git a/src/libs/libtelnet/Jamfile b/src/libs/libtelnet/Jamfile
index 452cccd9f8..254799dda1 100644
--- a/src/libs/libtelnet/Jamfile
+++ b/src/libs/libtelnet/Jamfile
@@ -1,7 +1,6 @@
 SubDir HAIKU_TOP src libs libtelnet ;
 
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
-SubDirCcFlags [ FDefines _BSD_SOURCE=1 ] ;
 
 StaticLibrary libtelnet.a :
 	auth.c
diff --git a/src/libs/util/Jamfile b/src/libs/util/Jamfile
index 29ad20f886..ce8b7db4d9 100644
--- a/src/libs/util/Jamfile
+++ b/src/libs/util/Jamfile
@@ -2,7 +2,7 @@ SubDir HAIKU_TOP src libs util ;
 
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 
-local defines = [ FDefines SCCSID=0 _BSD_SOURCE=1 ] ;
+local defines = [ FDefines SCCSID=0 ] ;
 SubDirCcFlags $(defines) ;
 
 local architectureObject ;
diff --git a/src/system/libnetwork/Jamfile b/src/system/libnetwork/Jamfile
index 74ec200afd..455b6f8783 100644
--- a/src/system/libnetwork/Jamfile
+++ b/src/system/libnetwork/Jamfile
@@ -6,8 +6,6 @@ UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility bsd ] : true ;
 local services = [ FGristFiles services ] ;
 SEARCH on $(services) = [ FDirName $(SUBDIR) netresolv defaults ] ;
 
-SubDirC++Flags [ FDefines _BSD_SOURCE=1 ] ;
-
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
 	on $(architectureObject) {
diff --git a/src/system/libnetwork/netresolv/Jamfile b/src/system/libnetwork/netresolv/Jamfile
index b1468c4444..8831aae6ca 100644
--- a/src/system/libnetwork/netresolv/Jamfile
+++ b/src/system/libnetwork/netresolv/Jamfile
@@ -23,7 +23,7 @@ for architectureObject in [ MultiArchSubDirSetup ] {
 			# we want to have the xxx_r functions, IPv6, and md5 implementation
 			# we also need to use our BSD compatibility functions
 			# and enable "lint" to remove the RCSID from all the files.
-			local defines = _REENTRANT=1 USE_MD5=1 _BSD_SOURCE INET6 lint LINT ;
+			local defines = _REENTRANT=1 USE_MD5=1 INET6 lint LINT ;
 			defines = [ FDefines $(defines) ] ;
 			SubDirCcFlags $(defines) -Wno-sign-compare ;
 			SubDirC++Flags $(defines) -Wno-sign-compare ;
diff --git a/src/tests/libs/bsd/wait4_test.cpp b/src/tests/libs/bsd/wait4_test.cpp
index 46f261551a..6685034306 100644
--- a/src/tests/libs/bsd/wait4_test.cpp
+++ b/src/tests/libs/bsd/wait4_test.cpp
@@ -9,7 +9,6 @@
 #include <stdio.h>
 #include <string.h>
 #include <sys/resource.h> 
-#define _BSD_SOURCE
 #include <sys/wait.h>
 #include <unistd.h>