diff -Naur gawk-4.2.1-orig/compile gawk-4.2.1/compile
--- gawk-4.2.1-orig/compile	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/compile	2018-12-09 13:15:39.613043700 +0300
@@ -53,7 +53,7 @@
 	  MINGW*)
 	    file_conv=mingw
 	    ;;
-	  CYGWIN*)
+	  CYGWIN* | MSYS*)
 	    file_conv=cygwin
 	    ;;
 	  *)
@@ -67,7 +67,7 @@
 	mingw/*)
 	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
 	  ;;
-	cygwin/*)
+	cygwin/*|msys/*)
 	  file=`cygpath -m "$file" || echo "$file"`
 	  ;;
 	wine/*)
diff -Naur gawk-4.2.1-orig/config.guess gawk-4.2.1/config.guess
--- gawk-4.2.1-orig/config.guess	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/config.guess	2018-12-09 13:15:04.030008500 +0300
@@ -883,6 +883,9 @@
     amd64:CYGWIN*:*:* | x86_64:CYGWIN*:*:*)
 	echo x86_64-unknown-cygwin
 	exit ;;
+    amd64:MSYS*:*:* | x86_64:MSYS*:*:*)
+	echo x86_64-unknown-msys
+	exit ;;
     prep*:SunOS:5.*:*)
 	echo powerpcle-unknown-solaris2"`echo "$UNAME_RELEASE"|sed -e 's/[^.]*//'`"
 	exit ;;
diff -Naur gawk-4.2.1-orig/config.rpath gawk-4.2.1/config.rpath
--- gawk-4.2.1-orig/config.rpath	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/config.rpath	2018-12-09 13:14:36.612440300 +0300
@@ -57,7 +57,7 @@
     aix*)
       wl='-Wl,'
       ;;
-    mingw* | cygwin* | pw32* | os2* | cegcc*)
+    mingw* | cygwin* | msys* | pw32* | os2* | cegcc*)
       ;;
     hpux9* | hpux10* | hpux11*)
       wl='-Wl,'
@@ -149,7 +149,7 @@
 hardcode_minus_L=no
 
 case "$host_os" in
-  cygwin* | mingw* | pw32* | cegcc*)
+  cygwin* | msys* | mingw* | pw32* | cegcc*)
     # FIXME: the MSVC++ port hasn't been tested in a loooong time
     # When not using gcc, we currently assume that we are using
     # Microsoft Visual C++.
@@ -198,7 +198,7 @@
         ld_shlibs=no
       fi
       ;;
-    cygwin* | mingw* | pw32* | cegcc*)
+    cygwin* | msys* | mingw* | pw32* | cegcc*)
       # hardcode_libdir_flag_spec is actually meaningless, as there is
       # no search path for DLLs.
       hardcode_libdir_flag_spec='-L$libdir'
@@ -348,7 +348,7 @@
       ;;
     bsdi[45]*)
       ;;
-    cygwin* | mingw* | pw32* | cegcc*)
+    cygwin* | msys* | mingw* | pw32* | cegcc*)
       # When not using gcc, we currently assume that we are using
       # Microsoft Visual C++.
       # hardcode_libdir_flag_spec is actually meaningless, as there is
@@ -533,7 +533,7 @@
   bsdi[45]*)
     library_names_spec='$libname$shrext'
     ;;
-  cygwin* | mingw* | pw32* | cegcc*)
+  cygwin* | msys* | mingw* | pw32* | cegcc*)
     shrext=.dll
     library_names_spec='$libname.dll.a $libname.lib'
     ;;
diff -Naur gawk-4.2.1-orig/extension/build-aux/ar-lib gawk-4.2.1/extension/build-aux/ar-lib
--- gawk-4.2.1-orig/extension/build-aux/ar-lib	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/extension/build-aux/ar-lib	2018-12-09 13:59:01.252849000 +0300
@@ -53,7 +53,7 @@
 	  MINGW*)
 	    file_conv=mingw
 	    ;;
-	  CYGWIN*)
+	  CYGWIN* | MSYS*)
 	    file_conv=cygwin
 	    ;;
 	  *)
@@ -65,7 +65,7 @@
 	mingw)
 	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
 	  ;;
-	cygwin)
+	cygwin|msys)
 	  file=`cygpath -m "$file" || echo "$file"`
 	  ;;
 	wine)
diff -Naur gawk-4.2.1-orig/extension/build-aux/compile gawk-4.2.1/extension/build-aux/compile
--- gawk-4.2.1-orig/extension/build-aux/compile	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/extension/build-aux/compile	2018-12-09 13:58:41.307708200 +0300
@@ -53,7 +53,7 @@
 	  MINGW*)
 	    file_conv=mingw
 	    ;;
-	  CYGWIN*)
+	  CYGWIN* | MSYS*)
 	    file_conv=cygwin
 	    ;;
 	  *)
@@ -67,7 +67,7 @@
 	mingw/*)
 	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
 	  ;;
-	cygwin/*)
+	cygwin/* | msys/*)
 	  file=`cygpath -m "$file" || echo "$file"`
 	  ;;
 	wine/*)
diff -Naur gawk-4.2.1-orig/extension/build-aux/config.guess gawk-4.2.1/extension/build-aux/config.guess
--- gawk-4.2.1-orig/extension/build-aux/config.guess	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/extension/build-aux/config.guess	2018-12-09 13:58:18.810421400 +0300
@@ -883,6 +883,9 @@
     amd64:CYGWIN*:*:* | x86_64:CYGWIN*:*:*)
 	echo x86_64-unknown-cygwin
 	exit ;;
+    amd64:MSYS*:*:* | x86_64:MSYS*:*:*)
+	echo x86_64-unknown-msys
+	exit ;;
     prep*:SunOS:5.*:*)
 	echo powerpcle-unknown-solaris2"`echo "$UNAME_RELEASE"|sed -e 's/[^.]*//'`"
 	exit ;;
diff -Naur gawk-4.2.1-orig/extension/build-aux/config.rpath gawk-4.2.1/extension/build-aux/config.rpath
--- gawk-4.2.1-orig/extension/build-aux/config.rpath	2018-02-25 20:00:29.000000000 +0300
+++ gawk-4.2.1/extension/build-aux/config.rpath	2018-12-09 13:57:53.878995400 +0300
@@ -57,7 +57,7 @@
     aix*)
       wl='-Wl,'
       ;;
-    mingw* | cygwin* | pw32* | os2* | cegcc*)
+    mingw* | cygwin* | msys* | pw32* | os2* | cegcc*)
       ;;
     hpux9* | hpux10* | hpux11*)
       wl='-Wl,'
@@ -149,7 +149,7 @@
 hardcode_minus_L=no
 
 case "$host_os" in
-  cygwin* | mingw* | pw32* | cegcc*)
+  cygwin* | msys* | mingw* | pw32* | cegcc*)
     # FIXME: the MSVC++ port hasn't been tested in a loooong time
     # When not using gcc, we currently assume that we are using
     # Microsoft Visual C++.
@@ -198,7 +198,7 @@
         ld_shlibs=no
       fi
       ;;
-    cygwin* | mingw* | pw32* | cegcc*)
+    cygwin* | msys* | mingw* | pw32* | cegcc*)
       # hardcode_libdir_flag_spec is actually meaningless, as there is
       # no search path for DLLs.
       hardcode_libdir_flag_spec='-L$libdir'
@@ -348,7 +348,7 @@
       ;;
     bsdi[45]*)
       ;;
-    cygwin* | mingw* | pw32* | cegcc*)
+    cygwin* | msys* | mingw* | pw32* | cegcc*)
       # When not using gcc, we currently assume that we are using
       # Microsoft Visual C++.
       # hardcode_libdir_flag_spec is actually meaningless, as there is
@@ -533,7 +533,7 @@
   bsdi[45]*)
     library_names_spec='$libname$shrext'
     ;;
-  cygwin* | mingw* | pw32* | cegcc*)
+  cygwin* | msys* | mingw* | pw32* | cegcc*)
     shrext=.dll
     library_names_spec='$libname.dll.a $libname.lib'
     ;;
diff -Naur gawk-4.2.1-orig/m4/threadlib.m4 gawk-4.2.1/m4/threadlib.m4
--- gawk-4.2.1-orig/m4/threadlib.m4	2017-12-14 20:53:45.000000000 +0300
+++ gawk-4.2.1/m4/threadlib.m4	2018-12-09 14:07:21.229446000 +0300
@@ -68,7 +68,7 @@
          dnl bugs that lead to endless loops or crashes. See
          dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
          osf*) gl_use_threads=no ;;
-         cygwin*)
+         cygwin* | msys*)
                case `uname -r` in
                  1.[0-5].*) gl_use_threads=no ;;
                  *)         gl_use_threads=yes ;;
diff -Naur gawk-4.2.1-orig/test/Makefile.am gawk-4.2.1/test/Makefile.am
--- gawk-4.2.1-orig/test/Makefile.am	2018-02-23 11:44:11.000000000 +0300
+++ gawk-4.2.1/test/Makefile.am	2018-12-09 14:08:42.865115300 +0300
@@ -1941,7 +1941,7 @@
 mbprintf5::
 	@echo $@ $(ZOS_FAIL)
 	@-case `uname` in \
-	CYGWIN* | MINGW32* | *MS-DOS*) echo this test fails on this system --- skipping $@ ;; \
+	CYGWIN* | MSYS* | MINGW32* | *MS-DOS*) echo this test fails on this system --- skipping $@ ;; \
 	*) \
 	[ -z "$$GAWKLOCALE" ] && GAWKLOCALE=en_US.UTF-8; export GAWKLOCALE ; \
 	$(AWK) -f "$(srcdir)"/$@.awk "$(srcdir)"/$@.in >_$@ 2>&1 || echo EXIT CODE: $$? >> _$@ ; \
@@ -2274,7 +2274,7 @@
 	IRIX) \
 	echo This test may fail on IRIX systems when run on an NFS filesystem.; \
 	echo If it does, try rerunning on an xfs filesystem. ;; \
-	CYGWIN*) \
+	CYGWIN* | MSYS*) \
 	echo This test may fail on CYGWIN systems when run on an NFS filesystem.; \
 	echo If it does, try rerunning on an ntfs filesystem. ;; \
 	esac
diff -Naur gawk-4.2.1-orig/test/Makefile.in gawk-4.2.1/test/Makefile.in
--- gawk-4.2.1-orig/test/Makefile.in	2018-02-25 20:06:29.000000000 +0300
+++ gawk-4.2.1/test/Makefile.in	2018-12-09 14:08:31.028438300 +0300
@@ -2381,7 +2381,7 @@
 mbprintf5::
 	@echo $@ $(ZOS_FAIL)
 	@-case `uname` in \
-	CYGWIN* | MINGW32* | *MS-DOS*) echo this test fails on this system --- skipping $@ ;; \
+	CYGWIN* | MSYS* | MINGW32* | *MS-DOS*) echo this test fails on this system --- skipping $@ ;; \
 	*) \
 	[ -z "$$GAWKLOCALE" ] && GAWKLOCALE=en_US.UTF-8; export GAWKLOCALE ; \
 	$(AWK) -f "$(srcdir)"/$@.awk "$(srcdir)"/$@.in >_$@ 2>&1 || echo EXIT CODE: $$? >> _$@ ; \
@@ -2714,7 +2714,7 @@
 	IRIX) \
 	echo This test may fail on IRIX systems when run on an NFS filesystem.; \
 	echo If it does, try rerunning on an xfs filesystem. ;; \
-	CYGWIN*) \
+	CYGWIN* | MSYS*) \
 	echo This test may fail on CYGWIN systems when run on an NFS filesystem.; \
 	echo If it does, try rerunning on an ntfs filesystem. ;; \
 	esac