diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..be233a2
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,476 @@
+PROJECT(maiko C)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.15)
+
+SET(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+SET(CMAKE_C_STANDARD 90)
+
+IF(CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_COMPILER_ID MATCHES "GNU")
+  IF(UNIX AND CMAKE_GENERATOR STREQUAL "Ninja")
+    SET(CMAKE_C_FLAGS "-fdiagnostics-color=always ${CMAKE_C_FLAGS}")
+  ENDIF()
+  SET(CMAKE_C_FLAGS "-funsigned-char -fno-strict-aliasing -fwrapv ${CMAKE_C_FLAGS}")
+ENDIF()
+
+INCLUDE(CheckLibraryExists)
+CHECK_LIBRARY_EXISTS(crypt crypt "" NEED_LIB_CRYPT)
+CHECK_LIBRARY_EXISTS(m fmod "" NEED_LIB_M)
+
+FIND_PACKAGE(X11 REQUIRED)
+
+SET(MAIKO_DEFINITIONS
+    "-DRELEASE=351"
+)
+
+IF(TRUE)
+  # Turn this into a config option.
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DNOPIXRECT"
+    "-DXWINDOW"
+  )
+ENDIF()
+
+IF(UNIX)
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DFORKCOMM"
+    "-DLOGINT"
+    "-DOLD_CURSOR"
+  )
+ENDIF()
+
+IF(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "amd64" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "AMD64" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "x86" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "i386" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "i686")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DBYTESWAP"
+  )
+ENDIF()
+
+IF(CMAKE_SYSTEM_PROCESSOR MATCHES "arm.*" OR
+   CMAKE_SYSTEM_PROCESSOR STREQUAL "aarch64")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DBYTESWAP"
+  )
+ENDIF()
+
+IF(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DMACOSX"
+    "-DNOFORN"
+  )
+ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DFREEBSD"
+    "-DNOFORN"
+  )
+ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DAIX" # This is temporary
+    "-DLINUX"
+    "-DNOFORN"
+  )
+ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+  LIST(APPEND MAIKO_DEFINITIONS
+    "-DAIX" # This is temporary
+    "-DOS5"
+  )
+ENDIF()
+
+IF(APPLE)
+  # Suppress "has no symbols" warnings when building static libraries on macOS:
+  # https://stackoverflow.com/questions/4929255/building-static-libraries-on-mac-using-cmake-and-gcc/33067191#33067191
+  SET(CMAKE_C_ARCHIVE_CREATE   "<CMAKE_AR> Scr <TARGET> <LINK_FLAGS> <OBJECTS>")
+  SET(CMAKE_C_ARCHIVE_FINISH   "<CMAKE_RANLIB> -no_warning_for_no_symbols -c <TARGET>")
+ENDIF()
+
+# These don't build on Linux. Some are for SunOS and DOS. Others ... ?
+SET(BAD_SRCS
+    src/atom.c
+    src/cdaudio.c
+    src/cdrom.c
+    src/chatter.c
+    src/Cldeetr.c
+    src/codeconv.c
+    src/codetbl.c
+    src/doscomm.c
+    src/doskbd.c
+    src/dosmouse.c
+    src/ejlisp.c
+    src/imagefile2.c
+    src/imagefile.c
+    src/keytst.c
+    src/kbdif.c
+    src/loader.c
+    src/lpdual.c
+    src/lpkit.c
+    src/lplexyy.c
+    src/lpmain.c
+    src/lpread.c
+    src/lpsolve.c
+    src/lptran.c
+    src/lpwrite.c
+    src/lpytab.c
+    src/mnwevent.c
+    src/mnxmeth.c
+    src/mouseif.c
+    src/oether.c
+    src/oldeether.c
+    src/optck.c
+    src/picture.c
+    src/rawcolor.c
+    src/rawrs232c.c
+    src/rs232c.c
+    src/testdsp.c
+    src/truecolor.c
+    src/tty.c
+    src/vesainit.c
+    src/vgainit.c
+)
+
+SET(MAIKO_SRCS
+    src/allocmds.c
+    src/arith2.c
+    src/arith3.c
+    src/arith4.c
+    src/array2.c
+    src/array3.c
+    src/array4.c
+    src/array5.c
+    src/array6.c
+    src/array.c
+    src/asmbbt.c
+    src/bbtsub.c
+    src/bin.c
+    src/binds.c
+    src/bitblt.c
+    src/blt.c
+    src/byteswap.c
+    src/car-cdr.c
+    src/chardev.c
+    src/common.c
+    src/conspage.c
+    src/dbgtool.c
+    src/dir.c
+    src/dlpi.c
+    src/draw.c
+    src/dsk.c
+    src/dspif.c
+    src/dspsubrs.c
+    src/eqf.c
+    src/ether.c
+    src/findkey.c
+    src/foreign.c
+    src/fp.c
+    src/fvar.c
+    src/gc2.c
+    src/gcarray.c
+    src/gc.c
+    src/gccode.c
+    src/gcfinal.c
+    src/gchtfind.c
+    src/gcmain3.c
+    src/gcoflow.c
+    src/gcr.c
+    src/gcrcell.c
+    src/gcscan.c
+    src/gvar2.c
+    src/hacks.c
+    src/hardrtn.c
+    src/inet.c
+    src/initdsp.c
+    src/initkbd.c
+    src/initsout.c
+    src/intcall.c
+    src/kbdsubrs.c
+    src/keyevent.c
+    src/keylib.c
+    src/keytstno.c
+    src/kprint.c
+    src/ldsout.c
+    src/lineblt8.c
+    src/lisp2c.c
+    src/llcolor.c
+    src/llstk.c
+    src/loopsops.c
+    src/lowlev1.c
+    src/lowlev2.c
+    src/lsthandl.c
+    src/misc7.c
+    src/miscn.c
+    src/mkatom.c
+    src/mkcell.c
+    src/mkkey.c
+    src/mvs.c
+    src/osmsg.c
+    src/perrno.c
+    src/return.c
+    src/rpc.c
+    src/rplcons.c
+    src/shift.c
+    src/storage.c
+    src/subr0374.c
+    src/subr.c
+    src/sxhash.c
+    src/sysatms.c
+    src/testtool.c
+    src/timer.c
+    src/typeof.c
+    src/ubf1.c
+    src/ubf2.c
+    src/ubf3.c
+    src/ufn.c
+    src/ufs.c
+    src/unixcomm.c
+    src/unwind.c
+    src/uraid.c
+    src/usrsubr.c
+    src/uutils.c
+    src/vars3.c
+    src/vmemsave.c
+    src/xbbt.c
+    src/xc.c
+    src/xcursor.c
+    src/xinit.c
+    src/xlspwin.c
+    src/xmkicon.c
+    src/xrdopt.c
+    src/xscroll.c
+    src/xwinman.c
+    src/z2.c
+)
+SET(MAIKO_HDRS
+    inc/address.h
+    inc/adr68k.h
+    inc/allocmdsdefs.h
+    inc/arith2defs.h
+    inc/arith2.h
+    inc/arith3defs.h
+    inc/arith4defs.h
+    inc/arith.h
+    inc/array2defs.h
+    inc/array3defs.h
+    inc/array4defs.h
+    inc/array5defs.h
+    inc/array6defs.h
+    inc/arraydefs.h
+    inc/array.h
+    inc/bb.h
+    inc/bbtsubdefs.h
+    inc/bbtsub.h
+    inc/bindefs.h
+    inc/bindsdefs.h
+    inc/bitbltdefs.h
+    inc/bitblt.h
+    inc/bltdefs.h
+    inc/byteswapdefs.h
+    inc/car-cdrdefs.h
+    inc/cdrom.h
+    inc/cell.h
+    inc/chardevdefs.h
+    inc/commondefs.h
+    inc/conspagedefs.h
+    inc/dbgtooldefs.h
+    inc/dbprint.h
+    inc/debug.h
+    inc/devconf.h
+    inc/devif.h
+    inc/dirdefs.h
+    inc/display.h
+    inc/dld.h
+    inc/drawdefs.h
+    inc/dskdefs.h
+    inc/dspdata.h
+    inc/dspifdefs.h
+    inc/dspsubrsdefs.h
+    inc/emlglob.h
+    inc/eqfdefs.h
+    inc/etherdefs.h
+    inc/ether.h
+    inc/fast_dsp.h
+    inc/findkeydefs.h
+    inc/fpdefs.h
+    inc/fvardefs.h
+    inc/gc2defs.h
+    inc/gcarraydefs.h
+    inc/gccodedefs.h
+    inc/gcdata.h
+    inc/gcdefs.h
+    inc/gcfinaldefs.h
+    inc/gchtfinddefs.h
+    inc/gcmain3defs.h
+    inc/gcoflowdefs.h
+    inc/gcrcelldefs.h
+    inc/gcrdefs.h
+    inc/gcscandefs.h
+    inc/gvar2defs.h
+    inc/hacksdefs.h
+    inc/hardrtndefs.h
+    inc/hdw_conf.h
+    inc/ifpage.h
+    inc/inetdefs.h
+    inc/initatms.h
+    inc/initdspdefs.h
+    inc/initkbddefs.h
+    inc/initsoutdefs.h
+    inc/inlineC.h
+    inc/inln386i.h
+    inc/inln68k.h
+    inc/inlndos.h
+    inc/inlnPS2.h
+    inc/inlnSPARC.h
+    inc/intcalldefs.h
+    inc/iopage.h
+    inc/kbdif.h
+    inc/kbdsubrsdefs.h
+    inc/keyboard.h
+    inc/keyeventdefs.h
+    inc/keylibdefs.h
+    inc/keysym.h
+    inc/kprintdefs.h
+    inc/ldeXdefs.h
+    inc/ldsoutdefs.h
+    inc/lineblt8defs.h
+    inc/lisp2cdefs.h
+    inc/lispemul.h
+    inc/lispmap.h
+    inc/lispver1.h
+    inc/lispver2.h
+    inc/llcolordefs.h
+    inc/lldsp.h
+    inc/llstkdefs.h
+    inc/locfile.h
+    inc/loopsopsdefs.h
+    inc/lowlev1defs.h
+    inc/lowlev2defs.h
+    inc/lpdefs.h
+    inc/lpglob.h
+    inc/lpglobl.h
+    inc/lpkit.h
+    inc/lppatch.h
+    inc/lpproto.h
+    inc/lspglob.h
+    inc/lsptypes.h
+    inc/lsthandldefs.h
+    inc/maindefs.h
+    inc/medleyfp.h
+    inc/misc7defs.h
+    inc/miscndefs.h
+    inc/miscstat.h
+    inc/mkatomdefs.h
+    inc/mkcelldefs.h
+    inc/mnxdefs.h
+    inc/mvsdefs.h
+    inc/my.h
+    inc/MyWindow.h
+    inc/native.h
+    inc/nfsfh.h
+    inc/nfswatch.h
+    inc/opcodes.h
+    inc/os.h
+    inc/osmsgdefs.h
+    inc/osmsg.h
+    inc/perrnodefs.h
+    inc/picture.h
+    inc/pilotbbt.h
+    inc/print.h
+    inc/profile.h
+    inc/rawrs232c.h
+    inc/returndefs.h
+    inc/return.h
+    inc/rpcdefs.h
+    inc/rplconsdefs.h
+    inc/rs232c.h
+    inc/shiftdefs.h
+    inc/stack.h
+    inc/storagedefs.h
+    inc/stream.h
+    inc/subr0374defs.h
+    inc/subrdefs.h
+    inc/subrs.h
+    inc/sxhashdefs.h
+    inc/sysatms.h
+    inc/testtooldefs.h
+    inc/timeout.h
+    inc/timerdefs.h
+    inc/tos1defs.h
+    inc/tosfns.h
+    inc/tosret.h
+    inc/tty.h
+    inc/typeofdefs.h
+    inc/ubf1defs.h
+    inc/ubf2defs.h
+    inc/ubf3defs.h
+    inc/ufsdefs.h
+    inc/unixcommdefs.h
+    inc/unixfork.h
+    inc/unwinddefs.h
+    inc/uraiddefs.h
+    inc/usrsubrdefs.h
+    inc/uutilsdefs.h
+    inc/vars3defs.h
+    inc/version.h
+    inc/vmemsavedefs.h
+    inc/vmemsave.h
+    inc/xbbtdefs.h
+    inc/Xbitblt.h
+    inc/xbitmaps.h
+    inc/xcdefs.h
+    inc/xcursordefs.h
+    inc/xdefs.h
+    inc/xinitdefs.h
+    inc/XKeymap.h
+    inc/xlspwindefs.h
+    inc/xmkicondefs.h
+    inc/xrdoptdefs.h
+    inc/xscrolldefs.h
+    inc/xscroll.h
+    inc/xwinmandefs.h
+    inc/z2defs.h
+)
+ADD_LIBRARY(maiko STATIC ${MAIKO_SRCS} ${MAIKO_HDRS})
+TARGET_COMPILE_DEFINITIONS(maiko PUBLIC ${MAIKO_DEFINITIONS})
+TARGET_INCLUDE_DIRECTORIES(maiko PUBLIC inc)
+TARGET_LINK_LIBRARIES(maiko X11::X11)
+IF(NEED_LIB_CRYPT)
+  TARGET_LINK_LIBRARIES(maiko crypt)
+ENDIF()
+IF(NEED_LIB_M)
+  TARGET_LINK_LIBRARIES(maiko m)
+ENDIF()
+
+ADD_CUSTOM_TARGET(gen-vdate
+  COMMAND mkvdate > vdate.c
+  BYPRODUCTS vdate.c
+)
+
+# keymaker  lde  ldeether  ldex  mkvdate  setsout  tstsout
+
+ADD_EXECUTABLE(keymaker src/keymaker.c)
+TARGET_LINK_LIBRARIES(keymaker maiko)
+
+ADD_EXECUTABLE(lde src/ldeboot.c src/unixfork.c)
+TARGET_COMPILE_DEFINITIONS(lde PUBLIC ${MAIKO_DEFINITIONS})
+TARGET_INCLUDE_DIRECTORIES(lde PUBLIC inc)
+TARGET_LINK_LIBRARIES(lde X11::X11)
+
+ADD_EXECUTABLE(ldeether src/ldeether.c)
+TARGET_COMPILE_DEFINITIONS(ldeether PUBLIC ${MAIKO_DEFINITIONS})
+TARGET_INCLUDE_DIRECTORIES(ldeether PUBLIC inc)
+
+ADD_EXECUTABLE(ldex src/main.c vdate.c)
+TARGET_LINK_LIBRARIES(ldex maiko)
+
+ADD_EXECUTABLE(mkvdate src/mkvdate.c)
+TARGET_COMPILE_DEFINITIONS(mkvdate PUBLIC ${MAIKO_DEFINITIONS})
+TARGET_INCLUDE_DIRECTORIES(mkvdate PUBLIC inc)
+
+# In the old build system, this didn't link in everything.
+ADD_EXECUTABLE(setsout src/setsout.c)
+TARGET_LINK_LIBRARIES(setsout maiko)
+
+# In the old build system, this didn't link in everything.
+ADD_EXECUTABLE(tstsout src/tstsout.c)
+TARGET_LINK_LIBRARIES(tstsout maiko)