diff --git a/ruby.spec b/ruby.spec
index 5c8fd23..12e1908 100644
--- a/ruby.spec
+++ b/ruby.spec
@@ -137,6 +137,9 @@
 %global test_unit_version 3.6.1
 %global typeprof_version 0.21.9
 
+# Bundled nkf version
+%global bundled_nkf_version 2.1.5
+
 %global tapset_libdir %(echo %{_libdir} | sed 's/64//')*
 
 %if 0%{?fedora} >= 19
@@ -167,7 +170,7 @@
 Summary: An interpreter of object-oriented scripting language
 Name: ruby
 Version: %{ruby_version}%{?development_release}
-Release: 5%{?dist}
+Release: 6%{?dist}
 # BSD-3-Clause: missing/{crypt,mt19937,setproctitle}.c
 # ISC: missing/strl{cat,cpy}.c
 # Public Domain for example for: include/ruby/st.h, strftime.c, missing/*, ...
@@ -336,6 +339,11 @@ Provides: bundled(ccan-check_type)
 Provides: bundled(ccan-container_of)
 Provides: bundled(ccan-list)
 
+# https://github.com/nurse/nkf
+# Please note that nkf going to be promoted to bundled gem in Ruby 3.4:
+# https://github.com/ruby/ruby/commit/2e3a7f70ae71650be6ea38a483f66ce17ca5eb1d
+Provides: bundled(nkf) = %{bundled_nkf_version}
+
 # StdLib default gems.
 Provides: bundled(rubygem-did_you_mean) = %{did_you_mean_version}
 Provides: bundled(rubygem-openssl) = %{openssl_version}
@@ -1073,6 +1081,16 @@ make -C %{_vpath_builddir} -s runruby TESTRUN_SCRIPT="-e \" \
   exit 1 if Bundler::URI::VERSION != '%{bundler_uri_version}'; \
 \""
 
+# Check bundled libraries versions.
+
+# Nkf.
+make -C %{_vpath_builddir} -s runruby TESTRUN_SCRIPT="-e \" \
+  require 'nkf'; \
+  puts '%%{bundled_nkf_version}: %{bundled_nkf_version}'; \
+  puts %Q[NKF::NKF_VERSION: #{NKF::NKF_VERSION}]; \
+  exit 1 if NKF::NKF_VERSION != '%{bundled_nkf_version}'; \
+\""
+
 
 # test_debug(TestRubyOptions) fails due to LoadError reported in debug mode,
 # when abrt.rb cannot be required (seems to be easier way then customizing
@@ -1668,6 +1686,9 @@ make -C %{_vpath_builddir} runruby TESTRUN_SCRIPT=" \
 
 
 %changelog
+* Fri Apr 12 2024 Vít Ondruch <vondruch@redhat.com> - 3.3.0-6
+- Add `bundled` provide for NKF.
+
 * Wed Mar 06 2024 Vít Ondruch <vondruch@redhat.com> - 3.3.0-5
 - Fix FTBFS caused by OpenSSL 3.2.1 update.