diff --git a/configure.ac b/configure.ac
index bd92bc4..bd2c0af 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3704,6 +3704,8 @@ if test "$gmp_asm_syntax_testing" != no; then
 	  case $host in
 	    *-*-darwin*)
 	      GMP_INCLUDE_MPN(arm64/darwin.m4) ;;
+	    *-pc-mingw32)
+	      GMP_INCLUDE_MPN(arm64/coff.m4) ;;
 	    *)
 	      GMP_INCLUDE_MPN(arm64/arm64-defs.m4) ;;
           esac
diff --git a/mpn/arm64/coff.m4 b/mpn/arm64/coff.m4
new file mode 100644
index 0000000..88605b3
--- /dev/null
+++ b/mpn/arm64/coff.m4
@@ -0,0 +1,54 @@
+divert(-1)
+
+dnl  m4 macros for ARM64 COFF assembler.
+
+dnl  Copyright 2020 Free Software Foundation, Inc.
+
+dnl  This file is part of the GNU MP Library.
+dnl
+dnl  The GNU MP Library is free software; you can redistribute it and/or modify
+dnl  it under the terms of either:
+dnl
+dnl    * the GNU Lesser General Public License as published by the Free
+dnl      Software Foundation; either version 3 of the License, or (at your
+dnl      option) any later version.
+dnl
+dnl  or
+dnl
+dnl    * the GNU General Public License as published by the Free Software
+dnl      Foundation; either version 2 of the License, or (at your option) any
+dnl      later version.
+dnl
+dnl  or both in parallel, as here.
+dnl
+dnl  The GNU MP Library is distributed in the hope that it will be useful, but
+dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+dnl  for more details.
+dnl
+dnl  You should have received copies of the GNU General Public License and the
+dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
+dnl  see https://www.gnu.org/licenses/.
+
+
+dnl  Standard commenting is with @, the default m4 # is for constants and we
+dnl  don't want to disable macro expansions in or after them.
+
+changecom
+
+
+dnl  LEA_HI(reg,gmp_symbol), LEA_LO(reg,gmp_symbol)
+dnl
+dnl  Load the address of gmp_symbol into a register. We split this into two
+dnl  parts to allow separation for manual insn scheduling.
+
+define(`LEA_HI', `ldr	$1, =$2')dnl
+define(`LEA_LO')dnl
+
+dnl  Usage: ALIGN(bytes)
+dnl
+dnl  Emit a ".align" directive.
+
+define(`ALIGN', `  .align 8')dnl
+
+divert`'dnl