diff --git a/common.mk b/common.mk
index 07e2008d08..0ff8f547f5 100644
--- a/common.mk
+++ b/common.mk
@@ -787,6 +787,7 @@ $(RBCONFIG): $(srcdir)/tool/mkconfig.rb config.status $(srcdir)/version.h
 		-install_name=$(RUBY_INSTALL_NAME) \
 		-so_name=$(RUBY_SO_NAME) \
 		-unicode_version=$(UNICODE_VERSION) \
+		-unicode_emoji_version=$(UNICODE_EMOJI_VERSION) \
 	> rbconfig.tmp
 	$(IFCHANGE) "--timestamp=$@" rbconfig.rb rbconfig.tmp
 
diff --git a/tool/mkconfig.rb b/tool/mkconfig.rb
index ec39e5f8bd..e9bedc6e44 100755
--- a/tool/mkconfig.rb
+++ b/tool/mkconfig.rb
@@ -9,6 +9,7 @@
 $install_name ||= nil
 $so_name ||= nil
 $unicode_version ||= nil
+$unicode_emoji_version ||= nil
 arch = $arch or raise "missing -arch"
 version = $version or raise "missing -version"
 
@@ -247,6 +248,9 @@ print(*v_others)
 print <<EOS if $unicode_version
   CONFIG["UNICODE_VERSION"] = #{$unicode_version.dump}
 EOS
+print <<EOS if $unicode_emoji_version
+  CONFIG["UNICODE_EMOJI_VERSION"] = #{$unicode_emoji_version.dump}
+EOS
 print <<EOS if /darwin/ =~ arch
   CONFIG["SDKROOT"] = ENV["SDKROOT"] || "" # don't run xcrun everytime, usually useless.
 EOS