diff --git a/pkgs/ruby/.rubocop.yml b/pkgs/ruby/.rubocop.yml
index 3b2fc4e..d04acb6 100644
--- a/pkgs/ruby/.rubocop.yml
+++ b/pkgs/ruby/.rubocop.yml
@@ -13,8 +13,6 @@ Layout/AccessModifierIndentation:
 
 Layout/LineLength:
   Max: 80
-  Exclude:
-    - 'spec/lib/kernaux/sprintf_spec.rb'
 
 Lint/AmbiguousOperatorPrecedence:
   Enabled: false
diff --git a/pkgs/ruby/spec/lib/kernaux/panic_spec.rb b/pkgs/ruby/spec/lib/kernaux/assert/panic_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/panic_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/assert/panic_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/itoa10_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/itoa10_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/itoa10_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/itoa10_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/itoa16_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/itoa16_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/itoa16_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/itoa16_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/itoa2_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/itoa2_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/itoa2_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/itoa2_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/itoa8_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/itoa8_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/itoa8_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/itoa8_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/itoa_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/itoa_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/itoa_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/itoa_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/utoa10_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/utoa10_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/utoa10_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/utoa10_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/utoa16_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/utoa16_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/utoa16_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/utoa16_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/utoa2_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/utoa2_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/utoa2_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/utoa2_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/utoa8_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/utoa8_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/utoa8_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/utoa8_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/utoa_spec.rb b/pkgs/ruby/spec/lib/kernaux/ntoa/utoa_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/utoa_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/ntoa/utoa_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb b/pkgs/ruby/spec/lib/kernaux/printf/snprintf1_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/snprintf1_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/printf/snprintf1_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/sprintf1_spec.rb b/pkgs/ruby/spec/lib/kernaux/printf/sprintf1_spec.rb
similarity index 100%
rename from pkgs/ruby/spec/lib/kernaux/sprintf1_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/printf/sprintf1_spec.rb
diff --git a/pkgs/ruby/spec/lib/kernaux/sprintf_spec.rb b/pkgs/ruby/spec/lib/kernaux/printf/sprintf_spec.rb
similarity index 84%
rename from pkgs/ruby/spec/lib/kernaux/sprintf_spec.rb
rename to pkgs/ruby/spec/lib/kernaux/printf/sprintf_spec.rb
index 34b9927..e7aa465 100644
--- a/pkgs/ruby/spec/lib/kernaux/sprintf_spec.rb
+++ b/pkgs/ruby/spec/lib/kernaux/printf/sprintf_spec.rb
@@ -4,7 +4,9 @@ require 'spec_helper'
 
 RSpec.describe KernAux, '.sprintf' do
   if described_class.singleton_class.method_defined? :sprintf
-    subject(:sprintf) { described_class.sprintf 'Hello, ', ['%s', 'World'], '!' }
+    subject :sprintf do
+      described_class.sprintf 'Hello, ', ['%s', 'World'], '!'
+    end
 
     it { is_expected.to be_instance_of String }
     it { is_expected.to be_frozen }
@@ -21,8 +23,10 @@ RSpec.describe KernAux, '.sprintf' do
       ['_orig', 'using original tests'],
     ].each do |(suffix, description)|
       context description do
-        printf_yml =
-          File.expand_path("../../../../../common/printf#{suffix}.yml", __dir__)
+        printf_yml = File.expand_path(
+          "../../../../../../common/printf#{suffix}.yml",
+          __dir__,
+        )
 
         YAML.safe_load_file(printf_yml).each do |test|
           expected = test['result']