diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 2548b21..0e76d3c 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -116,7 +116,8 @@ def getFullVersion():
 DEPSRC = os.path.join(WORKDIR, 'third-party')
 DEPSRC = os.path.expanduser('~/Universal/other-sources')
 
-universal_opts_map = { '32-bit': ('i386', 'ppc',),
+universal_opts_map = { 'universal2': ('arm64', 'x86_64'),
+                       '32-bit': ('i386', 'ppc',),
                        '64-bit': ('x86_64', 'ppc64',),
                        'intel':  ('i386', 'x86_64'),
                        'intel-32':  ('i386',),
@@ -124,6 +125,7 @@ def getFullVersion():
                        '3-way':  ('ppc', 'i386', 'x86_64'),
                        'all':    ('i386', 'ppc', 'x86_64', 'ppc64',) }
 default_target_map = {
+        'universal2': '10.9',
         '64-bit': '10.5',
         '3-way': '10.5',
         'intel': '10.5',
@@ -190,6 +192,27 @@ def getTargetCompilers():
 def internalTk():
     return getDeptargetTuple() >= (10, 6)
 
+
+def tweak_tcl_build(basedir, archList):
+    with open("Makefile", "r") as fp:
+        contents = fp.readlines()
+
+    # For reasons I don't understand the tcl configure script
+    # decides that some stdlib symbols aren't present, before
+    # deciding that strtod is broken.
+    new_contents = []
+    for line in contents:
+        if line.startswith("COMPAT_OBJS"):
+            # note: the space before strtod.o is intentional,
+            # the detection of a broken strtod results in
+            # "fixstrod.o" on this line.
+            for nm in ("strstr.o", "strtoul.o", " strtod.o"):
+                line = line.replace(nm, "")
+        new_contents.append(line)
+
+    with open("Makefile", "w") as fp:
+        fp.writelines(new_contents)
+
 # List of names of third party software built with this installer.
 # The names will be inserted into the rtf version of the License.
 THIRD_PARTY_LIBS = []
@@ -215,6 +238,9 @@ def library_recipes():
               buildrecipe=build_universal_openssl,
               configure=None,
               install=None,
+              patches=[
+                  "openssl-mac-arm64.patch",
+                   ],
           ),
     ])
 
@@ -231,6 +257,7 @@ def library_recipes():
                     '--libdir=/Library/Frameworks/Python.framework/Versions/%s/lib'%(getVersion(),),
               ],
               useLDFlags=False,
+              buildrecipe=tweak_tcl_build,
               install='make TCL_LIBRARY=%(TCL_LIBRARY)s && make install TCL_LIBRARY=%(TCL_LIBRARY)s DESTDIR=%(DESTDIR)s'%{
                   "DESTDIR": shellQuote(os.path.join(WORKDIR, 'libraries')),
                   "TCL_LIBRARY": shellQuote('/Library/Frameworks/Python.framework/Versions/%s/lib/tcl8.6'%(getVersion())),
@@ -801,6 +828,7 @@ def build_openssl_arch(archbase, arch):
         arch_opts = {
             "i386": ["darwin-i386-cc"],
             "x86_64": ["darwin64-x86_64-cc", "enable-ec_nistp_64_gcc_128"],
+            "arm64": ["darwin64-arm64-cc"],
             "ppc": ["darwin-ppc-cc"],
             "ppc64": ["darwin64-ppc-cc"],
         }
diff --git a/Mac/BuildScript/openssl-mac-arm64.patch b/Mac/BuildScript/openssl-mac-arm64.patch
new file mode 100644
index 0000000..11267fb
--- /dev/null
+++ b/Mac/BuildScript/openssl-mac-arm64.patch
@@ -0,0 +1,41 @@
+diff -ur openssl-1.1.1g-orig/Configurations/10-main.conf openssl-1.1.1g/Configurations/10-main.conf
+--- openssl-1.1.1g-orig/Configurations/10-main.conf	2020-04-21 14:22:39.000000000 +0200
++++ openssl-1.1.1g/Configurations/10-main.conf	2020-07-26 12:21:32.000000000 +0200
+@@ -1557,6 +1557,14 @@
+         bn_ops           => "SIXTY_FOUR_BIT_LONG",
+         perlasm_scheme   => "macosx",
+     },
++    "darwin64-arm64-cc" => {
++        inherit_from     => [ "darwin-common", asm("aarch64_asm") ],
++        CFLAGS           => add("-Wall"),
++        cflags           => add("-arch arm64"),
++        lib_cppflags     => add("-DL_ENDIAN"),
++        bn_ops           => "SIXTY_FOUR_BIT_LONG",
++        perlasm_scheme   => "ios64",
++    },
+ 
+ ##### GNU Hurd
+     "hurd-x86" => {
+diff -ur openssl-1.1.1g-orig/config openssl-1.1.1g/config
+--- openssl-1.1.1g-orig/config	2020-04-21 14:22:39.000000000 +0200
++++ openssl-1.1.1g/config	2020-07-26 12:21:59.000000000 +0200
+@@ -255,6 +255,9 @@
+ 		;;
+ 	    x86_64)
+ 		echo "x86_64-apple-darwin${VERSION}"
++                ;;
++	    arm64)
++		echo "arm64-apple-darwin${VERSION}"
+ 		;;
+ 	    *)
+ 		echo "i686-apple-darwin${VERSION}"
+@@ -497,6 +500,9 @@
+ 	else
+ 	    OUT="darwin64-x86_64-cc"
+ 	fi ;;
++  x86_64-apple-darwin*)
++	OUT="darwin64-arm64-cc"
++        ;;
+   armv6+7-*-iphoneos)
+ 	__CNF_CFLAGS="$__CNF_CFLAGS -arch armv6 -arch armv7"
+ 	__CNF_CXXFLAGS="$__CNF_CXXFLAGS -arch armv6 -arch armv7"