diff --git a/klib/src/platform/android/android.def b/klib/src/platform/android/android.def
index a327f5446eb..431fc33a6d4 100644
--- a/klib/src/platform/android/android.def
+++ b/klib/src/platform/android/android.def
@@ -1,5 +1,5 @@
 package = platform.android
-headers = android/api-level.h android/asset_manager.h android/asset_manager_jni.h android/bitmap.h \
+headers = jni.h android/api-level.h android/asset_manager.h android/asset_manager_jni.h android/bitmap.h \
      android/configuration.h android/dlext.h android/input.h android/keycodes.h android/log.h \
      android/looper.h android/native_activity.h android/native_window.h android/native_window_jni.h \
      android/obb.h android/rect.h android/sensor.h android/storage_manager.h android/tts.h \
diff --git a/klib/src/platform/android/linux.def b/klib/src/platform/android/linux.def
new file mode 100644
index 00000000000..610d7939890
--- /dev/null
+++ b/klib/src/platform/android/linux.def
@@ -0,0 +1,22 @@
+package = platform.linux
+headers = byteswap.h elf.h endian.h features.h lastlog.h link.h \
+    malloc.h mntent.h nsswitch.h pathconf.h termio.h thread_db.h time64.h \
+    uchar.h util.h \
+    sys/epoll.h sys/inotify.h sys/klog.h sys/sendfile.h \
+    sys/sysconf.h sys/sysinfo.h sys/utime.h \
+    net/if_ether.h net/if_packet.h netinet/ether.h netinet/in6.h netpacket/packet.h
+
+linkerOpts = -ldl
+
+---
+// cinterop -target android_arm32 -def klib/src/platform/android/posix.def -o platform.posix.klib
+
+// Wrapper to access errno variable.
+static int posix_errno() {
+        return errno;
+}
+
+// Wrapper to access h_errno variable.
+static int posix_h_errno() {
+        return h_errno;
+}
\ No newline at end of file
diff --git a/klib/src/platform/android/posix.def b/klib/src/platform/android/posix.def
index 533430f1566..1eef4fc000b 100644
--- a/klib/src/platform/android/posix.def
+++ b/klib/src/platform/android/posix.def
@@ -1,20 +1,18 @@
 package = platform.posix
-headers = alloca.h ar.h assert.h byteswap.h complex.h dirent.h dlfcn.h elf.h endian.h err.h errno.h fcntl.h \
-    features.h fenv.h fnmatch.h fts.h ftw.h getopt.h grp.h inttypes.h jni.h lastlog.h libgen.h limits.h \
-    link.h locale.h malloc.h math.h memory.h mntent.h netdb.h nsswitch.h pathconf.h paths.h poll.h \
+headers = alloca.h ar.h assert.h complex.h dirent.h dlfcn.h err.h errno.h fcntl.h \
+    fenv.h fnmatch.h fts.h ftw.h getopt.h grp.h inttypes.h libgen.h limits.h \
+    locale.h math.h memory.h netdb.h paths.h poll.h \
     pthread.h pwd.h regex.h resolv.h sched.h search.h semaphore.h setjmp.h sgtty.h signal.h \
-    stdatomic.h stdint.h stdio.h stdlib.h string.h strings.h syslog.h termio.h termios.h thread_db.h \
-    time.h time64.h uchar.h ucontext.h unistd.h util.h utime.h utmp.h wchar.h wctype.h xlocale.h \
-    zconf.h zlib.h \
-    sys/epoll.h sys/inotify.h sys/ioctl.h sys/ipc.h sys/klog.h sys/mman.h sys/poll.h sys/ptrace.h \
-    sys/queue.h sys/select.h sys/sendfile.h sys/shm.h sys/stat.h sys/sysconf.h sys/sysinfo.h \
-    sys/syslimits.h sys/time.h sys/times.h sys/utime.h sys/wait.h \
-    net/ethernet.h net/if.h net/if_arp.h net/if_ether.h net/if_packet.h net/if_types.h net/route.h \
-    netinet/ether.h netinet/icmp6.h netinet/if_ether.h netinet/in.h netinet/in6.h netinet/in_systm.h \
+    stdatomic.h stdint.h stdio.h stdlib.h string.h strings.h syslog.h termios.h \
+    time.h ucontext.h unistd.h utime.h utmp.h wchar.h wctype.h xlocale.h \
+    net/ethernet.h net/if.h net/if_arp.h net/route.h \
+    netinet/icmp6.h netinet/if_ether.h netinet/in.h netinet/in_systm.h \
     netinet/ip.h netinet/ip6.h netinet/ip_icmp.h netinet/tcp.h netinet/udp.h \
-    netpacket/packet.h
+    sys/ioctl.h sys/ipc.h sys/mman.h sys/poll.h sys/ptrace.h \
+    sys/queue.h sys/select.h sys/shm.h sys/stat.h \
+    sys/syslimits.h sys/time.h sys/times.h sys/wait.h
 
-linkerOpts = -ldl -lz
+linkerOpts = -ldl
 
 ---
 // cinterop -target android_arm32 -def klib/src/platform/android/posix.def -o platform.posix.klib
diff --git a/klib/src/platform/android/zlib.def b/klib/src/platform/android/zlib.def
new file mode 100644
index 00000000000..46ed691d1a3
--- /dev/null
+++ b/klib/src/platform/android/zlib.def
@@ -0,0 +1,3 @@
+package = platform.zlib
+headers = zconf.h zlib.h
+linkerOpts = -lz
diff --git a/klib/src/platform/linux/linux.def b/klib/src/platform/linux/linux.def
index dd7044c673c..0a43a3b609b 100644
--- a/klib/src/platform/linux/linux.def
+++ b/klib/src/platform/linux/linux.def
@@ -1,33 +1,36 @@
 package = platform.linux
-headers = aio.h aliases.h a.out.h argp.h argz.h cpio.h crypt.h \
-	ctype.h envz.h error.h execinfo.h fmtmsg.h fpu_control.h \
+headers = aio.h aliases.h a.out.h argp.h argz.h byteswap.h cpio.h crypt.h \
+	ctype.h elf.h endian.h envz.h error.h execinfo.h ffeatures.h mtmsg.h \
+	fpu_control.h \
 	fstab.h _G_config.h gconv.h glob.h gnu-versions.h \
-	gshadow.h iconv.h ieee754.h ifaddrs.h langinfo.h \
-	libintl.h libio.h mcheck.h monetary.h mqueue.h \
-	nl_types.h nss.h obstack.h printf.h pty.h re_comp.h \
+	gshadow.h iconv.h ieee754.h ifaddrs.h langinfo.h lastlog.h \
+	libintl.h libio.h link.h malloc.h mcheck.h mntent.h \
+	monetary.h mqueue.h \
+	nl_types.h nss.h nsswitch.h obstack.h \
+	pathconf.h printf.h pty.h re_comp.h \
 	spawn.h stab.h stdc-predef.h stdio_ext.h syscall.h \
-	tar.h ttyent.h ulimit.h ustat.h utmpx.h \
-	values.h wait.h wordexp.h \
+	tar.h termio.h thread_db.h time64.h ttyent.h uchar.h ulimit.h \
+	ustat.h util.h utmpx.h values.h wait.h wordexp.h \
 	arpa/ftp.h arpa/inet.h arpa/nameser_compat.h \
 	arpa/nameser.h arpa/telnet.h arpa/tftp.h \
+	net/if_ether.h net/if_packet.h net/if_types.h \
+	netinet/ether.h netinet/in6.h netpacket/packet.h \
 	sys/acct.h sys/auxv.h sys/bitypes.h sys/cdefs.h \
-	sys/debugreg.h sys/dir.h sys/errno.h \
+	sys/debugreg.h sys/dir.h sys/epoll.h sys/errno.h \
 	sys/eventfd.h sys/fanotify.h sys/fcntl.h \
 	sys/file.h sys/fsuid.h sys/gmon.h sys/gmon_out.h \
-	sys/io.h sys/kdaemon.h sys/kd.h sys/mount.h \
+	sys/inotify.h sys/io.h sys/kdaemon.h sys/kd.h sys/klog.h sys/mount.h \
 	sys/msg.h sys/mtio.h sys/param.h sys/pci.h sys/perm.h \
 	sys/personality.h sys/prctl.h sys/procfs.h sys/profil.h \
 	sys/raw.h sys/reboot.h sys/reg.h sys/resource.h \
 	sys/sem.h sys/sendfile.h sys/signalfd.h sys/signal.h \
 	sys/socket.h sys/socketvar.h sys/soundcard.h sys/statfs.h \
 	sys/statvfs.h sys/stropts.h sys/swap.h sys/syscall.h \
-	sys/sysctl.h sys/syslog.h sys/sysmacros.h sys/termios.h \
+	sys/sysctl.h sys/sysinfo.h sys/syslog.h sys/sysmacros.h sys/termios.h \
 	sys/timeb.h sys/timerfd.h sys/timex.h sys/ttychars.h \
 	sys/ttydefaults.h sys/types.h sys/ucontext.h sys/uio.h \
 	sys/ultrasound.h sys/un.h sys/unistd.h sys/user.h \
-	sys/ustat.h sys/utsname.h sys/vfs.h sys/vlimit.h \
+	sys/ustat.h sys/utime.h sys/utsname.h sys/vfs.h sys/vlimit.h \
 	sys/vt.h sys/vtimes.h sys/xattr.h
 
 compilerOpts = -D_GNU_SOURCE
-
-linkerOpts = -ldl
diff --git a/klib/src/platform/linux/posix.def b/klib/src/platform/linux/posix.def
index df969e68445..eb21ae3db99 100644
--- a/klib/src/platform/linux/posix.def
+++ b/klib/src/platform/linux/posix.def
@@ -1,30 +1,28 @@
 package = platform.posix
-headers = alloca.h ar.h assert.h byteswap.h complex.h dirent.h dlfcn.h elf.h endian.h err.h errno.h fcntl.h \
-    features.h fenv.h fnmatch.h fts.h ftw.h getopt.h grp.h inttypes.h lastlog.h libgen.h limits.h \
-    link.h locale.h malloc.h math.h memory.h mntent.h netdb.h paths.h poll.h \
+headers = alloca.h ar.h assert.h complex.h dirent.h dlfcn.h err.h errno.h fcntl.h \
+    fenv.h fnmatch.h fts.h ftw.h getopt.h grp.h inttypes.h libgen.h limits.h \
+    locale.h math.h memory.h netdb.h paths.h poll.h \
     pthread.h pwd.h regex.h resolv.h sched.h search.h semaphore.h setjmp.h sgtty.h signal.h \
-    stdatomic.h stdint.h stdio.h stdlib.h string.h strings.h syslog.h termio.h termios.h thread_db.h \
-    time.h uchar.h ucontext.h unistd.h utime.h utmp.h wchar.h wctype.h xlocale.h zconf.h zlib.h \
-     net/ethernet.h net/if.h net/if_arp.h net/if_packet.h net/route.h \
-    netinet/ether.h netinet/icmp6.h netinet/if_ether.h netinet/in.h netinet/in_systm.h \
+    stdatomic.h stdint.h stdio.h stdlib.h string.h strings.h syslog.h termios.h \
+    time.h ucontext.h unistd.h utime.h utmp.h wchar.h wctype.h xlocale.h \
+    net/ethernet.h net/if.h net/if_arp.h net/route.h \
+    netinet/icmp6.h netinet/if_ether.h netinet/in.h netinet/in_systm.h \
     netinet/ip.h netinet/ip6.h netinet/ip_icmp.h netinet/tcp.h netinet/udp.h \
-    netpacket/packet.h \
-    sys/epoll.h sys/inotify.h sys/ioctl.h sys/ipc.h sys/klog.h sys/mman.h sys/poll.h sys/ptrace.h \
-    sys/queue.h sys/select.h sys/shm.h sys/stat.h sys/sysinfo.h \
-    sys/time.h sys/times.h sys/wait.h
+    sys/ioctl.h sys/ipc.h sys/mman.h sys/poll.h sys/ptrace.h \
+    sys/queue.h sys/select.h sys/shm.h sys/stat.h \
+    sys/syslimits.h sys/time.h sys/times.h sys/wait.h
 
 compilerOpts = -D_GNU_SOURCE
-linkerOpts = -ldl -lz
 
 ---
 // cinterop -target linux -def klib/src/platform/linux/posix.def -o platform.posix.klib
 
 // Wrapper to access errno variable.
 static int posix_errno() {
-	return errno;
+    return errno;
 }
 
 // Wrapper to access h_errno variable.
 static int posix_h_errno() {
-	return h_errno;
+    return h_errno;
 }
diff --git a/klib/src/platform/linux/zlib.def b/klib/src/platform/linux/zlib.def
new file mode 100644
index 00000000000..46ed691d1a3
--- /dev/null
+++ b/klib/src/platform/linux/zlib.def
@@ -0,0 +1,3 @@
+package = platform.zlib
+headers = zconf.h zlib.h
+linkerOpts = -lz
diff --git a/klib/src/platform/osx/objc.def b/klib/src/platform/osx/objc.def
new file mode 100644
index 00000000000..e0423839c17
--- /dev/null
+++ b/klib/src/platform/osx/objc.def
@@ -0,0 +1,11 @@
+package = platform.objc
+headers = objc/List.h objc/NSObjCRuntime.h objc/NSObject.h objc/Object.h objc/Protocol.h \
+    objc/hashtable.h objc/hashtable2.h objc/message.h objc/objc-api.h \
+    objc/objc-class.h objc/objc-exception.h objc/objc-load.h objc/objc-runtime.h \
+    objc/objc-sync.h objc/objc.h objc/runtime.h
+
+compilerOpts = -D_XOPEN_SOURCE
+linkerOpts = -lobjc
+
+---
+// objc-auto.h is excluded so far due to interop issues.
diff --git a/klib/src/platform/osx/osx.def b/klib/src/platform/osx/osx.def
new file mode 100644
index 00000000000..f912b345dc4
--- /dev/null
+++ b/klib/src/platform/osx/osx.def
@@ -0,0 +1,33 @@
+package = platform.osx
+headers = AppleTextureEncoder.h AssertMacros.h Availability.h AvailabilityInternal.h \
+    AvailabilityMacros.h Block.h ConditionalMacros.h MacTypes.h NSSystemDirectories.h \
+    TargetConditionals.h __cxxabi_config.h _locale.h _types.h _wctype.h \
+    aio.h aliasdb.h asl.h bitstring.h bootparams.h bootstrap.h bzlib.h \
+    cache.h cache_callbacks.h checkint.h com_err.h compression.h copyfile.h \
+    cpio.h crt_externs.h ctype.h curses.h cxxabi.h db.h \
+    disktab.h dns.h dns_sd.h dns_util.h dtrace.h eti.h execinfo.h expat.h \
+    expat_external.h fmtmsg.h form.h fsproperties.h fstab.h get_compat.h \
+    gethostuuid.h glob.h gssapi.h histedit.h ifaddrs.h inttypes.h iso646.h \
+    krb5.h langinfo.h launch.h lber.h lber_types.h ldap.h ldap_cdefs.h ldap_features.h \
+    ldap_schema.h ldap_utf8.h ldif.h libc.h libcharset.h \
+    libgen.h libproc.h libunwind.h localcharset.h \
+    membership.h monetary.h monitor.h mpool.h \
+    nameser.h nc_tparm.h ncurses.h ncurses_dll.h ndbm.h nl_types.h \
+    nlist.h notify.h notify_keys.h ntsid.h \
+    panel.h pcap-bpf.h pcap-namedb.h pcap.h printerdb.h printf.h \
+    profile.h ranlib.h readpassphrase.h removefile.h rune.h \
+    runetype.h sandbox.h slapi-plugin.h stab.h standards.h strhash.h \
+    stringlist.h struct.h sysdir.h sysexits.h tar.h term.h \
+    term_entry.h termcap.h tic.h timeconv.h ttyent.h tzfile.h \
+    unctrl.h unwind.h util.h utmpx.h vis.h vproc.h wordexp.h xattr_flags.h \
+    atm/atm_types.h bank/bank_types.h bsm/libbsm.h corpses/task_corpse.h \
+    hfs/hfs_format.h hfs/hfs_mount.h hfs/hfs_unistr.h \
+    os/activity.h os/availability.h os/base.h os/lock.h \
+    os/object.h os/overflow.h os/trace.h
+
+compilerOpts = -D_XOPEN_SOURCE
+linkerOpts = -ldl -lz
+
+---
+
+// menu.h is excluded so far due to interop issues.
\ No newline at end of file
diff --git a/klib/src/platform/osx/posix.def b/klib/src/platform/osx/posix.def
new file mode 100644
index 00000000000..55751cf4b06
--- /dev/null
+++ b/klib/src/platform/osx/posix.def
@@ -0,0 +1,29 @@
+package = platform.posix
+headers = alloca.h ar.h assert.h complex.h dirent.h dlfcn.h err.h errno.h fcntl.h \
+    fenv.h fnmatch.h fts.h ftw.h getopt.h grp.h inttypes.h libgen.h limits.h \
+    locale.h math.h memory.h netdb.h paths.h poll.h \
+    pthread.h pwd.h regex.h resolv.h sched.h search.h semaphore.h setjmp.h sgtty.h signal.h \
+    stdatomic.h stdint.h stdio.h stdlib.h string.h strings.h syslog.h termios.h \
+    time.h ucontext.h unistd.h utime.h utmp.h wchar.h wctype.h xlocale.h \
+    net/ethernet.h net/if.h net/if_arp.h net/route.h \
+    netinet/icmp6.h netinet/if_ether.h netinet/in.h netinet/in_systm.h \
+    netinet/ip.h netinet/ip6.h netinet/ip_icmp.h netinet/tcp.h netinet/udp.h \
+    sys/ioctl.h sys/ipc.h sys/mman.h sys/poll.h sys/ptrace.h \
+    sys/queue.h sys/select.h sys/shm.h sys/stat.h \
+    sys/syslimits.h sys/time.h sys/times.h sys/wait.h
+
+compilerOpts = -D_XOPEN_SOURCE
+linkerOpts = -ldl
+
+---
+// cinterop -def klib/src/platform/osx/posix.def -o platform.posix.klib
+
+// Wrapper to access errno variable.
+static int posix_errno() {
+    return errno;
+}
+
+// Wrapper to access h_errno variable.
+static int posix_h_errno() {
+    return h_errno;
+}
diff --git a/klib/src/platform/osx/zlib.def b/klib/src/platform/osx/zlib.def
new file mode 100644
index 00000000000..46ed691d1a3
--- /dev/null
+++ b/klib/src/platform/osx/zlib.def
@@ -0,0 +1,3 @@
+package = platform.zlib
+headers = zconf.h zlib.h
+linkerOpts = -lz