diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 7069c86..33f9af6 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -26,6 +26,10 @@ jobs:
         bundler-cache: true
     - name: Tests for Ruby ${{ matrix.ruby }}
       run: bundle exec rake
+    - uses: qltysh/qlty-action/coverage@v2
+      with:
+        token: ${{ secrets.QLTY_COVERAGE_TOKEN }}
+        files: coverage/.resultset.json
   # CodeClimate has become qlth.sh, this integration is currently broken.
   # coverage:
   #   needs: test
@@ -43,6 +47,7 @@ jobs:
   #       CC_TEST_REPORTER_ID: ${{ secrets.CC_TEST_REPORTER_ID }}
   #     with:
   #       coverageCommand: bundle exec rake
+
   yard:
     runs-on: ubuntu-latest
     env:
diff --git a/.qlty/.gitignore b/.qlty/.gitignore
new file mode 100644
index 0000000..3036618
--- /dev/null
+++ b/.qlty/.gitignore
@@ -0,0 +1,7 @@
+*
+!configs
+!configs/**
+!hooks
+!hooks/**
+!qlty.toml
+!.gitignore
diff --git a/.qlty/qlty.toml b/.qlty/qlty.toml
new file mode 100644
index 0000000..2f50e17
--- /dev/null
+++ b/.qlty/qlty.toml
@@ -0,0 +1,79 @@
+# This file was automatically generated by `qlty init`.
+# You can modify it to suit your needs.
+# We recommend you to commit this file to your repository.
+#
+# This configuration is used by both Qlty CLI and Qlty Cloud.
+#
+#     Qlty CLI -- Code quality toolkit for developers
+#     Qlty Cloud -- Fully automated Code Health Platform
+#
+# Try Qlty Cloud: https://qlty.sh
+#
+# For a guide to configuration, visit https://qlty.sh/d/config
+# Or for a full reference, visit https://qlty.sh/d/qlty-toml
+config_version = "0"
+
+exclude_patterns = [
+  "*_min.*",
+  "*-min.*",
+  "*.min.*",
+  "**/.yarn/**",
+  "**/*.d.ts",
+  "**/assets/**",
+  "**/bower_components/**",
+  "**/build/**",
+  "**/cache/**",
+  "**/config/**",
+  "**/db/**",
+  "**/deps/**",
+  "**/dist/**",
+  "**/extern/**",
+  "**/external/**",
+  "**/generated/**",
+  "**/Godeps/**",
+  "**/gradlew/**",
+  "**/mvnw/**",
+  "**/node_modules/**",
+  "**/protos/**",
+  "**/seed/**",
+  "**/target/**",
+  "**/templates/**",
+  "**/testdata/**",
+  "**/vendor/**",
+]
+
+test_patterns = [
+  "**/test/**",
+  "**/spec/**",
+  "**/*.test.*",
+  "**/*.spec.*",
+  "**/*_test.*",
+  "**/*_spec.*",
+  "**/test_*.*",
+  "**/spec_*.*",
+]
+
+[smells]
+mode = "comment"
+
+[smells.boolean_logic]
+threshold = 4
+
+[smells.file_complexity]
+threshold = 55
+
+[smells.return_statements]
+threshold = 4
+
+[smells.nested_control_flow]
+threshold = 4
+
+[smells.function_parameters]
+threshold = 4
+
+[smells.function_complexity]
+threshold = 5
+
+[[source]]
+name = "default"
+default = true
diff --git a/.rubocop.yml b/.rubocop.yml
index ddc5b73..1a8689e 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,6 +1,6 @@
 inherit_from: .rubocop_todo.yml
 
-require:
+plugins:
   - rubocop-rake
   - rubocop-rspec
 
diff --git a/lib/ruby_units/math.rb b/lib/ruby_units/math.rb
index 303d582..6801c90 100644
--- a/lib/ruby_units/math.rb
+++ b/lib/ruby_units/math.rb
@@ -112,9 +112,9 @@ def atan(number)
     # @return [RubyUnits::Unit] if parameters are units
     # @raise [ArgumentError] if parameters are not numbers or compatible units
     def atan2(x, y)
-      raise ArgumentError, "Incompatible RubyUnits::Units" if (x.is_a?(RubyUnits::Unit) && y.is_a?(RubyUnits::Unit)) && !x.compatible?(y)
+      raise ArgumentError, "Incompatible RubyUnits::Units" if x.is_a?(RubyUnits::Unit) && y.is_a?(RubyUnits::Unit) && !x.compatible?(y)
 
-      if (x.is_a?(RubyUnits::Unit) && y.is_a?(RubyUnits::Unit)) && x.compatible?(y)
+      if x.is_a?(RubyUnits::Unit) && y.is_a?(RubyUnits::Unit) && x.compatible?(y)
         [super(x.base_scalar, y.base_scalar), "radian"].to_unit
       else
         super
diff --git a/lib/ruby_units/unit.rb b/lib/ruby_units/unit.rb
index 53d558b..ed730db 100644
--- a/lib/ruby_units/unit.rb
+++ b/lib/ruby_units/unit.rb
@@ -180,7 +180,7 @@ def self.inherited(subclass)
 
     # setup internal arrays and hashes
     # @return [Boolean]
-    def self.setup
+    def self.setup # rubocop:disable Naming/PredicateMethod
       clear_cache
       self.prefix_values = {}
       self.prefix_map = {}
@@ -275,7 +275,7 @@ def self.cached
     end
 
     # @return [Boolean]
-    def self.clear_cache
+    def self.clear_cache # rubocop:disable Naming/PredicateMethod
       cached.clear
       base_unit_cache.clear
       new(1)
@@ -556,7 +556,7 @@ def initialize(*options)
         _opt_scalar, opt_units = self.class.parse_into_numbers_and_units(options[0])
         if !(self.class.cached.keys.include?(opt_units) ||
                 (opt_units =~ %r{\D/[\d+.]+}) ||
-                (opt_units =~ %r{(#{self.class.temp_regex})|(#{STONE_LB_UNIT_REGEX})|(#{LBS_OZ_UNIT_REGEX})|(#{FEET_INCH_UNITS_REGEX})|%|(#{TIME_REGEX})|i\s?(.+)?|±|\+/-})) && (opt_units && !opt_units.empty?)
+                (opt_units =~ %r{(#{self.class.temp_regex})|(#{STONE_LB_UNIT_REGEX})|(#{LBS_OZ_UNIT_REGEX})|(#{FEET_INCH_UNITS_REGEX})|%|(#{TIME_REGEX})|i\s?(.+)?|±|\+/-})) && opt_units && !opt_units.empty?
           self.class.cached.set(opt_units, scalar == 1 ? self : opt_units.to_unit)
         end
       end
@@ -682,17 +682,17 @@ def to_s(target_units = nil, precision: 0.0001, format: RubyUnits.configuration.
         feet, inches = convert_to("in").scalar.abs.divmod(12)
         improper, frac = inches.divmod(1)
         frac = frac.zero? ? "" : "-#{frac.rationalize(precision)}"
-        out = "#{negative? ? '-' : nil}#{feet}'#{improper}#{frac}\""
+        out = "#{'-' if negative?}#{feet}'#{improper}#{frac}\""
       when :lbs
         pounds, ounces = convert_to("oz").scalar.abs.divmod(16)
         improper, frac = ounces.divmod(1)
         frac = frac.zero? ? "" : "-#{frac.rationalize(precision)}"
-        out  = "#{negative? ? '-' : nil}#{pounds}#{separator}lbs #{improper}#{frac}#{separator}oz"
+        out  = "#{'-' if negative?}#{pounds}#{separator}lbs #{improper}#{frac}#{separator}oz"
       when :stone
         stone, pounds = convert_to("lbs").scalar.abs.divmod(14)
         improper, frac = pounds.divmod(1)
         frac = frac.zero? ? "" : "-#{frac.rationalize(precision)}"
-        out = "#{negative? ? '-' : nil}#{stone}#{separator}stone #{improper}#{frac}#{separator}lbs"
+        out = "#{'-' if negative?}#{stone}#{separator}stone #{improper}#{frac}#{separator}lbs"
       when String
         out = case target_units.strip
               when /\A\s*\Z/ # whitespace only
@@ -1309,7 +1309,7 @@ def units(with_prefix: true, format: nil)
               .uniq
               .map { [_1, output_denominator.count(_1)] }
               .map { |element, power| (element.to_s.strip + (power > 1 ? "^#{power}" : "")) }
-        "#{on.join('*')}#{od.empty? ? '' : "/#{od.join('*')}"}".strip
+        "#{on.join('*')}#{"/#{od.join('*')}" unless od.empty?}".strip
       end
     end
 
@@ -1768,7 +1768,7 @@ def parse(passed_unit_string = "0")
 
       # eliminate all known terms from this string.  This is a quick check to see if the passed unit
       # contains terms that are not defined.
-      used = "#{top} #{bottom}".to_s.gsub(self.class.unit_match_regex, "").gsub(%r{[\d*, "'_^/$]}, "")
+      used = "#{top} #{bottom}".gsub(self.class.unit_match_regex, "").gsub(%r{[\d*, "'_^/$]}, "")
       raise(ArgumentError, "'#{passed_unit_string}' Unit not recognized") unless used.empty?
 
       @numerator = @numerator.map do |item|
diff --git a/spec/ruby_units/math_spec.rb b/spec/ruby_units/math_spec.rb
index a9fe8c2..09fa295 100644
--- a/spec/ruby_units/math_spec.rb
+++ b/spec/ruby_units/math_spec.rb
@@ -25,7 +25,7 @@
     end
 
     context "with 'PI/4 radians' unit" do
-      subject(:angle) { RubyUnits::Unit.new((Math::PI / 4), "radians") }
+      subject(:angle) { RubyUnits::Unit.new(Math::PI / 4, "radians") }
 
       specify { expect(Math.sin(angle)).to be_within(0.01).of(0.70710678) }
       specify { expect(Math.cos(angle)).to be_within(0.01).of(0.70710678) }