diff --git a/configure.ac b/configure.ac
index 7068fbe..42310d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -122,25 +122,48 @@ AC_ARG_ENABLE([asan],
 AC_SUBST([LIBPSL_SO_VERSION], [8:0:3])
 AC_SUBST([LIBPSL_VERSION], $VERSION)
 
+#
+# Check for Win32
+#
+
+AC_MSG_CHECKING([for Win32])
+case "$host" in
+  *-*-mingw*)
+    os_win32=yes
+    ;;
+  *)
+    os_win32=no
+    ;;
+esac
+AC_MSG_RESULT([$os_win32])
+AM_CONDITIONAL(OS_WIN32, [test $os_win32 = yes])
+
+# Windows does not have langinfo.h, which the libidn/libidn2
+# builtin and runtime need, so default to ICU
+if test "x$os_win32" = "xyes" ; then
+  default_runtime=libicu
+  default_builtin=libicu
+else
+  default_runtime=libidn2
+  default_builtin=libidn2
+fi
+
 # Check for enable/disable builtin PSL data
 AC_ARG_ENABLE(runtime,
   [
   --enable-runtime[[=IDNA library]]
       Specify the IDNA library used for libpsl run-time conversions:
-        libidn2 [[default]]: IDNA2008 library (also needs libunistring)
-        libicu:            IDNA2008 UTS#46 library
-        libidn:            IDNA2003 library (also needs libunistring)
+        libidn2 [[default on non-Windows]]: IDNA2008 library (also needs libunistring)
+        libicu [[default on Windows]]:      IDNA2008 UTS#46 library
+        libidn:                           IDNA2003 library (also needs libunistring)
   --disable-runtime        Do not link runtime IDNA functionality
   ], [
     if test "$enableval" = "libidn2" -o "$enableval" = "yes"; then
       enable_runtime=libidn2
-      AC_DEFINE([WITH_LIBIDN2], [1], [generate PSL data using libidn2])
     elif test "$enableval" = "libicu"; then
       enable_runtime=libicu
-      AC_DEFINE([WITH_LIBICU], [1], [generate PSL data using libicu])
     elif test "$enableval" = "libidn"; then
       enable_runtime=libidn
-      AC_DEFINE([WITH_LIBIDN], [1], [generate PSL data using libidn])
     elif test "$enableval" = "no"; then
       enable_runtime=no
     else
@@ -148,8 +171,7 @@ AC_ARG_ENABLE(runtime,
     fi
   ], [
     # this is the default if neither --enable-runtime nor --disable-runtime were specified
-    enable_runtime=libidn2
-    AC_DEFINE([WITH_LIBIDN2], [1], [generate PSL data using libidn2])
+    enable_runtime=$default_runtime
   ])
 
 # Check for enable/disable builtin PSL data
@@ -157,20 +179,17 @@ AC_ARG_ENABLE(builtin,
   [
   --enable-builtin[[=IDNA library]]
       Specify the IDNA library used for built-in data generation:
-        libidn2 [[default]]: IDNA2008 library (also needs libunistring)
-        libicu: IDNA2008   UTS#46 library
-        libidn:            IDNA2003 library (also needs libunistring)
+        libidn2 [[default on non-Windows]]: IDNA2008 library (also needs libunistring)
+        libicu: [[default on Windows]]:     IDNA2008 UTS#46 library
+        libidn:                           IDNA2003 library (also needs libunistring)
   --disable-builtin        Do not generate built-in PSL data
   ], [
     if test "$enableval" = "libidn2" -o "$enableval" = "yes"; then
       enable_builtin=libidn2
-      AC_DEFINE([BUILTIN_GENERATOR_LIBIDN2], [1], [generate PSL data using libidn2])
     elif test "$enableval" = "libicu"; then
       enable_builtin=libicu
-      AC_DEFINE([BUILTIN_GENERATOR_LIBICU], [1], [generate PSL data using libicu])
     elif test "$enableval" = "libidn"; then
       enable_builtin=libidn
-      AC_DEFINE([BUILTIN_GENERATOR_LIBIDN], [1], [generate PSL data using libidn])
     elif test "$enableval" = "no"; then
       enable_builtin=no
     else
@@ -178,8 +197,7 @@ AC_ARG_ENABLE(builtin,
     fi
   ], [
     # this is the default if neither --enable-builtin nor --disable-builtin were specified
-    enable_builtin=libidn2
-    AC_DEFINE([BUILTIN_GENERATOR_LIBIDN2], [1], [generate PSL data using libidn2])
+    enable_builtin=$default_builtin
   ])
 
 if test "$enable_runtime" = "libicu" -o "$enable_builtin" = "libicu"; then
@@ -205,6 +223,15 @@ if test "$enable_runtime" = "libicu" -o "$enable_builtin" = "libicu"; then
   ])
 fi
 
+if test "x$HAVE_LIBICU" = "xyes" ; then
+  if test "$enable_runtime" = "libicu" ; then
+    AC_DEFINE([WITH_LIBICU], [1], [generate PSL data using libicu])
+  fi
+  if test "$enable_builtin" = "libicu" ; then
+    AC_DEFINE([BUILTIN_GENERATOR_LIBICU], [1], [generate PSL data using libicu])
+  fi
+fi
+
 if test "$enable_runtime" = "libidn2" -o "$enable_builtin" = "libidn2"; then
   # Check for libidn2
   PKG_CHECK_MODULES([LIBIDN2], [libidn2], [
@@ -219,6 +246,15 @@ if test "$enable_runtime" = "libidn2" -o "$enable_builtin" = "libidn2"; then
   ])
 fi
 
+if test "x$HAVE_LIBIDN2" = "xyes" ; then
+  if test "$enable_runtime" = "libidn2" ; then
+    AC_DEFINE([WITH_LIBIDN2], [1], [generate PSL data using libidn2])
+  fi
+  if test "$enable_builtin" = "libidn2" ; then
+    AC_DEFINE([BUILTIN_GENERATOR_LIBIDN2], [1], [generate PSL data using libidn2])
+  fi
+fi
+
 if test "$enable_runtime" = "libidn" -o "$enable_builtin" = "libidn"; then
   # Check for libidn
   PKG_CHECK_MODULES([LIBIDN], [libidn], [
@@ -233,6 +269,15 @@ if test "$enable_runtime" = "libidn" -o "$enable_builtin" = "libidn"; then
   ])
 fi
 
+if test "x$HAVE_LIBIDN2" = "xyes" ; then
+  if test "$enable_runtime" = "libidn" ; then
+    AC_DEFINE([WITH_LIBIDN], [1], [generate PSL data using libidn])
+  fi
+  if test "$enable_builtin" = "libidn" ; then
+    AC_DEFINE([BUILTIN_GENERATOR_LIBIDN], [1], [generate PSL data using libidn])
+  fi
+fi
+
 if test "x$HAVE_LIBIDN2" = "xyes" -o "x$HAVE_LIBIDN" = "xyes"; then
   # Check for libunistring, we need it for psl_str_to_utf8lower()
   OLDLIBS=$LIBS
@@ -265,6 +310,11 @@ elif test -n "$NEEDS_NSL" ; then
   LIBS="$LIBS -lnsl"
 fi
 
+# Windows has the networking functions in -lws2_32
+if test "x$os_win32" = "xyes" ; then
+  LIBS="$LIBS -lws2_32"
+fi
+
 # Check for clock_gettime() used for performance measurement
 AC_SEARCH_LIBS(clock_gettime, rt)
 
diff --git a/fuzz/Makefile.am b/fuzz/Makefile.am
index f98d186..1cd01ca 100644
--- a/fuzz/Makefile.am
+++ b/fuzz/Makefile.am
@@ -50,7 +50,15 @@ endif
 endif
 endif
 
-check_PROGRAMS = $(PSL_TESTS)
+# We don't have fmemopen() on Windows, so we can't run these tests
+# on Windows, at least for now
+
+check_PROGRAMS =
+TESTS =
+
+if !OS_WIN32
+  check_PROGRAMS += $(PSL_TESTS)
+endif
 
 dist-hook:
 	find . -name '*.options' -exec cp -v '{}' $(distdir) ';'
@@ -59,7 +67,10 @@ dist-hook:
 	find . -name '*.repro' -exec cp -vr '{}' $(distdir) ';'
 
 TESTS_ENVIRONMENT = TESTS_VALGRIND="@VALGRIND_ENVIRONMENT@"
-TESTS = $(PSL_TESTS)
+
+if !OS_WIN32
+  TESTS += $(PSL_TESTS)
+endif
 
 clean-local:
 	rm -rf *.gc?? *.log lcov coverage.info *_fuzzer *.o
diff --git a/src/Makefile.am b/src/Makefile.am
index 85eed13..dd6e33e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -24,6 +24,10 @@ if WITH_LIBIDN
   libpsl_la_LDFLAGS += -lidn -lunistring
 endif
 
+if OS_WIN32
+  libpsl_la_LDFLAGS += -no-undefined
+endif
+
 # Build rule for suffix_dafsa.c
 # PSL_FILE can be set by ./configure --with-psl-file=[PATH]
 suffixes_dafsa.c: $(PSL_FILE) $(srcdir)/psl-make-dafsa