diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index aee24287b..20969f1d4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -50,15 +50,16 @@ jobs:
           mongodb-version: 4.0
       - name: Check out repository code
         uses: actions/checkout@v4
-      - name: Do some action caching
-        uses: actions/cache@v3
         with:
-          path: vendor/bundle
-          key: ${{ runner.os }}-gems-${{ matrix.ruby }}-${{ matrix.rails }}-${{ hashFiles('**/Gemfile.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-gems-${{ matrix.ruby }}-${{ matrix.rails }}-
+          # Install gems/npm packages from GitHub fails without this
+          persist-credentials: false
       - name: Install libpq-dev
         run: sudo apt-get -yqq install libpq-dev
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          cache: 'npm'
+      - run: npm clean-install
       - name: Set up Ruby ${{ matrix.ruby }}
         uses: ruby/setup-ruby@v1
         with:
diff --git a/.github/workflows/examples.yml b/.github/workflows/examples.yml
index 69a2738a2..39c8800d2 100644
--- a/.github/workflows/examples.yml
+++ b/.github/workflows/examples.yml
@@ -51,15 +51,13 @@ jobs:
           mongodb-version: 4.0
       - name: Check out repository code
         uses: actions/checkout@v4
-      - name: Do some action caching
-        uses: actions/cache@v3
-        with:
-          path: vendor/bundle
-          key: ${{ runner.os }}-gems-${{ matrix.ruby }}-${{ matrix.rails }}-${{ hashFiles('**/Gemfile.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-gems-${{ matrix.ruby }}-${{ matrix.rails }}-
       - name: Install libpq-dev
         run: sudo apt-get -yqq install libpq-dev
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          cache: 'npm'
+      - run: npm clean-install
       - name: Set up Ruby ${{ matrix.ruby }}
         uses: ruby/setup-ruby@v1
         with:
diff --git a/.gitignore b/.gitignore
index 76cea35a6..8b4f94266 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,4 +21,5 @@ log
 .sass-cache
 bin
 .DS_Store
+node_modules
 .tool-versions
diff --git a/Guardfile b/Guardfile
index 4777b30ee..ee0570a03 100644
--- a/Guardfile
+++ b/Guardfile
@@ -22,6 +22,9 @@ guard 'rspec', rspec_options do
   watch(/shared_adapter_specs\.rb$/) { 'spec' }
   watch('spec/helper.rb') { 'spec' }
 
+  watch(%r{lib/flipper/expressions}) { 'spec/flipper/expressions_schema_spec.rb' }
+  watch(%r{node_modules/@flippercloud.io/expressions}) { 'spec/flipper/expressions_schema_spec.rb' }
+
   # To run all specs on every change... (useful with focus and fit)
   # watch(%r{.*}) { 'spec' }
 end
diff --git a/Rakefile b/Rakefile
index e72667b9f..2aadb6456 100644
--- a/Rakefile
+++ b/Rakefile
@@ -7,6 +7,7 @@ require 'flipper/version'
 # gem uninstall flipper flipper-ui flipper-redis
 desc 'Build gem into the pkg directory'
 task :build do
+  sh 'npm clean-install --silent'
   FileUtils.rm_rf('pkg')
   Dir['*.gemspec'].each do |gemspec|
     system "gem build #{gemspec}"
diff --git a/flipper-expressions-schema.gemspec b/flipper-expressions-schema.gemspec
new file mode 100644
index 000000000..c5ad9c72b
--- /dev/null
+++ b/flipper-expressions-schema.gemspec
@@ -0,0 +1,37 @@
+# -*- encoding: utf-8 -*-
+require File.expand_path('../lib/flipper/version', __FILE__)
+require File.expand_path('../lib/flipper/metadata', __FILE__)
+
+Gem::Specification.new do |gem|
+  SCHEMAS_DIR = File.expand_path("node_modules/@flippercloud.io/expressions/schemas", __dir__)
+
+  # Ensure schemas are downloaded when installed as a git dependency.
+  # This will be handled by rake when the gem is built and published.
+  Gem.post_install do
+    unless File.exist?(SCHEMAS_DIR)
+      warn "Getting schemas from @flippercloud.io/expressions..."
+      Dir.chdir(__dir__) { exec "npm install --silent" }
+    end
+  end
+
+  gem.authors       = ['John Nunemaker']
+  gem.email         = 'support@flippercloud.io'
+  gem.summary       = 'ActiveRecord adapter for Flipper'
+  gem.license       = 'MIT'
+  gem.homepage      = 'https://www.flippercloud.io/docs/expressions'
+
+  gem.files         = [
+    'package.json',
+    'package-lock.json',
+    'lib/flipper-expressions-schema.rb',
+    'lib/flipper/expression/schema.rb',
+    'lib/flipper/version.rb',
+  ] + Dir['node_modules/@flippercloud.io/expressions/schemas/*.json']
+  gem.name          = 'flipper-expressions-schema'
+  gem.require_paths = ['lib']
+  gem.version       = Flipper::VERSION
+  gem.metadata      = Flipper::METADATA
+
+  gem.add_dependency 'flipper', "~> #{Flipper::VERSION}"
+  gem.add_dependency 'json_schemer', '~> 1.0'
+end
diff --git a/flipper.gemspec b/flipper.gemspec
index ca48c66a8..d0bb068dd 100644
--- a/flipper.gemspec
+++ b/flipper.gemspec
@@ -6,7 +6,7 @@ plugin_files = []
 plugin_test_files = []
 
 Dir['flipper-*.gemspec'].map do |gemspec|
-  spec = eval(File.read(gemspec))
+  spec = Bundler.load_gemspec(gemspec)
   plugin_files << spec.files
   plugin_test_files << spec.files
 end
diff --git a/lib/flipper-expressions-schema.rb b/lib/flipper-expressions-schema.rb
new file mode 100644
index 000000000..23dafb71e
--- /dev/null
+++ b/lib/flipper-expressions-schema.rb
@@ -0,0 +1 @@
+require "flipper/expression/schema"
diff --git a/lib/flipper/expression.rb b/lib/flipper/expression.rb
index 8d08988c0..a4370569e 100644
--- a/lib/flipper/expression.rb
+++ b/lib/flipper/expression.rb
@@ -10,14 +10,18 @@ def self.build(object)
 
       case object
       when Hash
-        name = object.keys.first
-        args = object.values.first
-        unless name
+        if(object.keys.size != 1)
           raise ArgumentError, "#{object.inspect} cannot be converted into an expression"
         end
 
-        new(name, Array(args).map { |o| build(o) })
-      when String, Numeric, FalseClass, TrueClass
+        name = object.keys.first
+        args = object.values.first
+
+        # Ensure args are an array, but we can't just use Array(args) because it will convert a Hash to Array
+        args = args.is_a?(Hash) ? [args] : Array(args)
+
+        new(name, args.map { |o| build(o) })
+      when String, Numeric, FalseClass, TrueClass, nil
         Expression::Constant.new(object)
       when Symbol
         Expression::Constant.new(object.to_s)
@@ -56,6 +60,10 @@ def value
       }
     end
 
+    def validate
+      Schema.new.validate(value)
+    end
+
     private
 
     def call_with_context?
diff --git a/lib/flipper/expression/constant.rb b/lib/flipper/expression/constant.rb
index 35edca9e4..351d8ae7f 100644
--- a/lib/flipper/expression/constant.rb
+++ b/lib/flipper/expression/constant.rb
@@ -20,6 +20,10 @@ def eql?(other)
         other.is_a?(self.class) && other.value == value
       end
       alias_method :==, :eql?
+
+      def validate
+        Schema.new.validate(value)
+      end
     end
   end
 end
diff --git a/lib/flipper/expression/schema.rb b/lib/flipper/expression/schema.rb
new file mode 100644
index 000000000..7d44f71be
--- /dev/null
+++ b/lib/flipper/expression/schema.rb
@@ -0,0 +1,33 @@
+require "json_schemer"
+
+module Flipper
+  class Expression
+    class Schema < JSONSchemer::Schema::Draft7
+      PATH = Pathname.new(File.expand_path("../../../node_modules/@flippercloud.io/expressions", __dir__))
+
+      def self.schemas
+        @schemas ||=
+          Hash[
+            PATH
+              .glob("schemas/*.json")
+              .map { |path| [File.basename(path), JSON.parse(File.read(path))] }
+          ]
+      end
+
+      def self.examples
+        PATH
+          .glob("examples/*.json")
+          .map { |path| [File.basename(path), JSON.parse(File.read(path))] }
+      end
+
+      def initialize(schema = self.class.schemas["schema.json"])
+        super(
+          schema,
+          insert_property_defaults: true,
+          ref_resolver:
+            lambda { |url| self.class.schemas[File.basename(url.path)] }
+        )
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/add.rb b/lib/flipper/expressions/add.rb
new file mode 100644
index 000000000..ef02e469d
--- /dev/null
+++ b/lib/flipper/expressions/add.rb
@@ -0,0 +1,9 @@
+module Flipper
+  module Expressions
+    class Add
+      def self.call(left, right)
+        left + right
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/divide.rb b/lib/flipper/expressions/divide.rb
new file mode 100644
index 000000000..b242bc3e4
--- /dev/null
+++ b/lib/flipper/expressions/divide.rb
@@ -0,0 +1,9 @@
+module Flipper
+  module Expressions
+    class Divide
+      def self.call(left, right)
+        left / right
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/duration.rb b/lib/flipper/expressions/duration.rb
index b1ca50747..2a11ba658 100644
--- a/lib/flipper/expressions/duration.rb
+++ b/lib/flipper/expressions/duration.rb
@@ -11,7 +11,7 @@ class Duration
         "year" => 31_556_952 # length of a gregorian year (365.2425 days)
       }.freeze
 
-      def self.call(scalar, unit = 'second')
+      def self.call(scalar, unit)
         unit = unit.to_s.downcase.chomp("s")
 
         unless scalar.is_a?(Numeric)
diff --git a/lib/flipper/expressions/max.rb b/lib/flipper/expressions/max.rb
new file mode 100644
index 000000000..489b999b0
--- /dev/null
+++ b/lib/flipper/expressions/max.rb
@@ -0,0 +1,11 @@
+require "flipper/expression"
+
+module Flipper
+  module Expressions
+    class Max
+      def self.call(*args)
+        args.max
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/min.rb b/lib/flipper/expressions/min.rb
new file mode 100644
index 000000000..c3bef5a71
--- /dev/null
+++ b/lib/flipper/expressions/min.rb
@@ -0,0 +1,11 @@
+require "flipper/expression"
+
+module Flipper
+  module Expressions
+    class Min
+      def self.call(*args)
+        args.min
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/multiply.rb b/lib/flipper/expressions/multiply.rb
new file mode 100644
index 000000000..cb9002d99
--- /dev/null
+++ b/lib/flipper/expressions/multiply.rb
@@ -0,0 +1,9 @@
+module Flipper
+  module Expressions
+    class Multiply
+      def self.call(left, right)
+        left * right
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/percentage.rb b/lib/flipper/expressions/percentage.rb
index ec79713a5..bdad81461 100644
--- a/lib/flipper/expressions/percentage.rb
+++ b/lib/flipper/expressions/percentage.rb
@@ -2,7 +2,7 @@ module Flipper
   module Expressions
     class Percentage
       def self.call(value)
-        value.to_f.clamp(0, 100)
+        value.clamp(0, 100)
       end
     end
   end
diff --git a/lib/flipper/expressions/percentage_of_actors.rb b/lib/flipper/expressions/percentage_of_actors.rb
index 869c2a2ad..efadab6b2 100644
--- a/lib/flipper/expressions/percentage_of_actors.rb
+++ b/lib/flipper/expressions/percentage_of_actors.rb
@@ -5,7 +5,7 @@ class PercentageOfActors
 
       def self.call(text, percentage, context: {})
         prefix = context[:feature_name] || ""
-        Zlib.crc32("#{prefix}#{text}") % (100 * SCALING_FACTOR) < percentage * SCALING_FACTOR
+        Zlib.crc32("#{prefix}#{text}") % (100 * SCALING_FACTOR) < percentage.clamp(0, 100) * SCALING_FACTOR
       end
     end
   end
diff --git a/lib/flipper/expressions/subtract.rb b/lib/flipper/expressions/subtract.rb
new file mode 100644
index 000000000..fcd0026f1
--- /dev/null
+++ b/lib/flipper/expressions/subtract.rb
@@ -0,0 +1,9 @@
+module Flipper
+  module Expressions
+    class Subtract
+      def self.call(left, right)
+        left - right
+      end
+    end
+  end
+end
diff --git a/lib/flipper/expressions/time.rb b/lib/flipper/expressions/time.rb
index 93780749a..0c8dd83c7 100644
--- a/lib/flipper/expressions/time.rb
+++ b/lib/flipper/expressions/time.rb
@@ -2,7 +2,7 @@ module Flipper
   module Expressions
     class Time
       def self.call(value)
-        ::Time.parse(value)
+        ::Time.iso8601(value)
       end
     end
   end
diff --git a/lib/flipper/gates/expression.rb b/lib/flipper/gates/expression.rb
index 53d4dc31e..2e3ac91df 100644
--- a/lib/flipper/gates/expression.rb
+++ b/lib/flipper/gates/expression.rb
@@ -39,7 +39,7 @@ def open?(context)
       end
 
       def protects?(thing)
-        thing.is_a?(Flipper::Expression) || thing.is_a?(Hash)
+        thing.is_a?(Flipper::Expression) || thing.is_a?(Flipper::Expression::Constant) || thing.is_a?(Hash)
       end
 
       def wrap(thing)
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 000000000..abf445e83
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,99 @@
+{
+  "name": "flipper",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "dependencies": {
+        "@flippercloud.io/expressions": "github:flippercloud/expressions"
+      }
+    },
+    "node_modules/@flippercloud.io/expressions": {
+      "version": "1.0.0",
+      "resolved": "git+ssh://git@github.com/flippercloud/expressions.git#82e357d922ce6b00d343ba67900f749d0655b62c",
+      "license": "MIT",
+      "dependencies": {
+        "ajv": "^8.12.0",
+        "ajv-formats": "^2.1.1",
+        "uuid": "^9.0.0"
+      }
+    },
+    "node_modules/ajv": {
+      "version": "8.12.0",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.12.0.tgz",
+      "integrity": "sha512-sRu1kpcO9yLtYxBKvqfTeh9KzZEwO3STyX1HT+4CaDzC6HpTGYhIhPIzj9XuKU7KYDwnaeh5hcOwjy1QuJzBPA==",
+      "dependencies": {
+        "fast-deep-equal": "^3.1.1",
+        "json-schema-traverse": "^1.0.0",
+        "require-from-string": "^2.0.2",
+        "uri-js": "^4.2.2"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/epoberezkin"
+      }
+    },
+    "node_modules/ajv-formats": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/ajv-formats/-/ajv-formats-2.1.1.tgz",
+      "integrity": "sha512-Wx0Kx52hxE7C18hkMEggYlEifqWZtYaRgouJor+WMdPnQyEK13vgEWyVNup7SoeeoLMsr4kf5h6dOW11I15MUA==",
+      "dependencies": {
+        "ajv": "^8.0.0"
+      },
+      "peerDependencies": {
+        "ajv": "^8.0.0"
+      },
+      "peerDependenciesMeta": {
+        "ajv": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/fast-deep-equal": {
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
+      "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
+    },
+    "node_modules/json-schema-traverse": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/json-schema-traverse/-/json-schema-traverse-1.0.0.tgz",
+      "integrity": "sha512-NM8/P9n3XjXhIZn1lLhkFaACTOURQXjWhV4BA/RnOv8xvgqtqpAX9IO4mRQxSx1Rlo4tqzeqb0sOlruaOy3dug=="
+    },
+    "node_modules/punycode": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.0.tgz",
+      "integrity": "sha512-rRV+zQD8tVFys26lAGR9WUuS4iUAngJScM+ZRSKtvl5tKeZ2t5bvdNFdNHBW9FWR4guGHlgmsZ1G7BSm2wTbuA==",
+      "engines": {
+        "node": ">=6"
+      }
+    },
+    "node_modules/require-from-string": {
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/require-from-string/-/require-from-string-2.0.2.tgz",
+      "integrity": "sha512-Xf0nWe6RseziFMu+Ap9biiUbmplq6S9/p+7w7YXP/JBHhrUDDUhwa+vANyubuqfZWTveU//DYVGsDG7RKL/vEw==",
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
+    "node_modules/uri-js": {
+      "version": "4.4.1",
+      "resolved": "https://registry.npmjs.org/uri-js/-/uri-js-4.4.1.tgz",
+      "integrity": "sha512-7rKUyy33Q1yc98pQ1DAmLtwX109F7TIfWlW1Ydo8Wl1ii1SeHieeh0HHfPeL2fMXK6z0s8ecKs9frCuLJvndBg==",
+      "dependencies": {
+        "punycode": "^2.1.0"
+      }
+    },
+    "node_modules/uuid": {
+      "version": "9.0.1",
+      "resolved": "https://registry.npmjs.org/uuid/-/uuid-9.0.1.tgz",
+      "integrity": "sha512-b+1eJOlsR9K8HJpow9Ok3fiWOWSIcIzXodvv0rQjVoOVNpWMpxf1wZNpt4y9h10odCNrqnYp1OBzRktckBe3sA==",
+      "funding": [
+        "https://github.com/sponsors/broofa",
+        "https://github.com/sponsors/ctavan"
+      ],
+      "bin": {
+        "uuid": "dist/bin/uuid"
+      }
+    }
+  }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 000000000..4d3b4f9a5
--- /dev/null
+++ b/package.json
@@ -0,0 +1,6 @@
+{
+  "private": true,
+  "dependencies": {
+    "@flippercloud.io/expressions": "github:flippercloud/expressions"
+  }
+}
diff --git a/script/bootstrap b/script/bootstrap
index adccebf92..a06aaa9c2 100755
--- a/script/bootstrap
+++ b/script/bootstrap
@@ -19,3 +19,4 @@ cd $(dirname "$0")/..
 
 rm -rf .bundle/{binstubs,config}
 bundle install --binstubs --quiet "$@"
+npm clean-install --silent
diff --git a/spec/flipper/expression/schema_spec.rb b/spec/flipper/expression/schema_spec.rb
new file mode 100644
index 000000000..83ac4dfe8
--- /dev/null
+++ b/spec/flipper/expression/schema_spec.rb
@@ -0,0 +1,42 @@
+require "json_schemer"
+require "flipper-expressions-schema"
+
+RSpec.describe Flipper::Expression::Schema do
+  let(:schema) { Flipper::Expression::Schema.new }
+
+  Flipper::Expression::Schema.examples.each do |name, examples|
+    describe(name) do
+      examples["valid"].each do |example|
+        expression, context, result = example.values_at("expression", "context", "result")
+        context&.transform_keys!(&:to_sym)
+
+        describe expression.inspect do
+          it "is valid" do
+            errors = Flipper::Expression.build(expression).validate
+            expect(errors.to_a).to eq([])
+          end
+
+          it "evaluates to #{result.inspect}#{" with context " + context.inspect if context}" do
+            evaluated_result = Flipper::Expression.build(expression).evaluate(context || {})
+            expected_schema = JSONSchemer.schema(result)
+            expect(expected_schema.validate(evaluated_result).to_a).to eq([])
+          end
+        end
+      end
+
+      examples["invalid"].each do |example|
+        context example.inspect do
+          it "is invalid" do
+            expect(schema.valid?(example)).not_to be(true)
+          end
+
+          it "should not evaluate" do
+            expect { Flipper::Expression.build(example).evaluate }.to raise_error { |error|
+              expect([ArgumentError, TypeError, NoMethodError]).to include(error.class)
+            }
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/flipper/expressions/all_spec.rb b/spec/flipper/expressions/all_spec.rb
deleted file mode 100644
index c12fe54ac..000000000
--- a/spec/flipper/expressions/all_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-RSpec.describe Flipper::Expressions::All do
-  describe "#call" do
-    it "returns true if all args evaluate as true" do
-      expect(described_class.call(true, true)).to be(true)
-    end
-
-    it "returns false if any args evaluate as false" do
-      expect(described_class.call(false, true)).to be(false)
-    end
-
-    it "returns true with empty args" do
-      expect(described_class.call).to be(true)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/any_spec.rb b/spec/flipper/expressions/any_spec.rb
deleted file mode 100644
index cd6b07f8a..000000000
--- a/spec/flipper/expressions/any_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-RSpec.describe Flipper::Expressions::Any do
-  describe "#call" do
-    it "returns true if any args evaluate as true" do
-      expect(described_class.call(true, false)).to be(true)
-    end
-
-    it "returns false if all args evaluate as false" do
-      expect(described_class.call(false, false)).to be(false)
-    end
-
-    it "returns false with empty args" do
-      expect(described_class.call).to be(false)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/boolean_spec.rb b/spec/flipper/expressions/boolean_spec.rb
deleted file mode 100644
index c85921e79..000000000
--- a/spec/flipper/expressions/boolean_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-RSpec.describe Flipper::Expressions::Boolean do
-  describe "#call" do
-    [true, 'true', 1, '1'].each do |value|
-      it "returns a true for #{value.inspect}" do
-        expect(described_class.call(value)).to be(true)
-      end
-    end
-
-    [false, 'false', 0, '0', nil].each do |value|
-      it "returns a true for #{value.inspect}" do
-        expect(described_class.call(value)).to be(false)
-      end
-    end
-  end
-end
diff --git a/spec/flipper/expressions/duration_spec.rb b/spec/flipper/expressions/duration_spec.rb
deleted file mode 100644
index e19e2aff0..000000000
--- a/spec/flipper/expressions/duration_spec.rb
+++ /dev/null
@@ -1,43 +0,0 @@
-RSpec.describe Flipper::Expressions::Duration do
-  describe "#call" do
-    it "raises error with invalid value" do
-      expect { described_class.call(false, 'minute') }.to raise_error(ArgumentError)
-    end
-
-    it "raises error with invalid unit" do
-      expect { described_class.call(4, 'score') }.to raise_error(ArgumentError)
-    end
-
-    it 'defaults unit to seconds' do
-      expect(described_class.call(10)).to eq(10)
-    end
-
-    it "evaluates seconds" do
-      expect(described_class.call(10, 'seconds')).to eq(10)
-    end
-
-    it "evaluates minutes" do
-      expect(described_class.call(2, 'minutes')).to eq(120)
-    end
-
-    it "evaluates hours" do
-      expect(described_class.call(2, 'hours')).to eq(7200)
-    end
-
-    it "evaluates days" do
-      expect(described_class.call(2, 'days')).to eq(172_800)
-    end
-
-    it "evaluates weeks" do
-      expect(described_class.call(2, 'weeks')).to eq(1_209_600)
-    end
-
-    it "evaluates months" do
-      expect(described_class.call(2, 'months')).to eq(5_259_492)
-    end
-
-    it "evaluates years" do
-      expect(described_class.call(2, 'years')).to eq(63_113_904)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/equal_spec.rb b/spec/flipper/expressions/equal_spec.rb
deleted file mode 100644
index a2722810d..000000000
--- a/spec/flipper/expressions/equal_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-RSpec.describe Flipper::Expressions::Equal do
-  describe "#call" do
-    it "returns true when equal" do
-      expect(described_class.call("basic", "basic")).to be(true)
-    end
-
-    it "returns false when not equal" do
-      expect(described_class.call("basic", "plus")).to be(false)
-    end
-
-    it "returns false when value evaluates to nil" do
-      expect(described_class.call(nil, 1)).to be(false)
-      expect(described_class.call(1, nil)).to be(false)
-    end
-
-    it "raises ArgumentError with no arguments" do
-      expect { described_class.call }.to raise_error(ArgumentError)
-    end
-
-    it "raises ArgumentError with one argument" do
-      expect { described_class.call(10) }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/greater_than_or_equal_to_spec.rb b/spec/flipper/expressions/greater_than_or_equal_to_spec.rb
deleted file mode 100644
index 7e2e065a8..000000000
--- a/spec/flipper/expressions/greater_than_or_equal_to_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-RSpec.describe Flipper::Expressions::GreaterThanOrEqualTo do
-  describe "#call" do
-    it "returns true when equal" do
-      expect(described_class.call(2, 2)).to be(true)
-    end
-
-    it "returns true when greater" do
-      expect(described_class.call(2, 1)).to be(true)
-    end
-
-    it "returns false when less" do
-      expect(described_class.call(1, 2)).to be(false)
-    end
-
-    it "returns false when value evaluates to nil" do
-      expect(described_class.call(nil, 1)).to be(false)
-      expect(described_class.call(1, nil)).to be(false)
-    end
-
-    it "raises ArgumentError with no arguments" do
-      expect { described_class.call }.to raise_error(ArgumentError)
-    end
-
-    it "raises ArgumentError with one argument" do
-      expect { described_class.call(10) }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/greater_than_spec.rb b/spec/flipper/expressions/greater_than_spec.rb
deleted file mode 100644
index 9a89a858a..000000000
--- a/spec/flipper/expressions/greater_than_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-RSpec.describe Flipper::Expressions::GreaterThan do
-  describe "#call" do
-    it "returns false when equal" do
-      expect(described_class.call(2, 2)).to be(false)
-    end
-
-    it "returns true when greater" do
-      expect(described_class.call(2, 1)).to be(true)
-    end
-
-    it "returns false when less" do
-      expect(described_class.call(1, 2)).to be(false)
-    end
-
-    it "returns false when value evaluates to nil" do
-      expect(described_class.call(nil, 1)).to be(false)
-      expect(described_class.call(1, nil)).to be(false)
-    end
-
-    it "raises ArgumentError with no arguments" do
-      expect { described_class.call }.to raise_error(ArgumentError)
-    end
-
-    it "raises ArgumentError with one argument" do
-      expect { described_class.call(10) }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/less_than_or_equal_to_spec.rb b/spec/flipper/expressions/less_than_or_equal_to_spec.rb
deleted file mode 100644
index 9fa1182cc..000000000
--- a/spec/flipper/expressions/less_than_or_equal_to_spec.rb
+++ /dev/null
@@ -1,28 +0,0 @@
-RSpec.describe Flipper::Expressions::LessThanOrEqualTo do
-  describe "#call" do
-    it "returns true when equal" do
-      expect(described_class.call(2, 2)).to be(true)
-    end
-
-    it "returns true when less" do
-      expect(described_class.call(1, 2)).to be(true)
-    end
-
-    it "returns false when greater" do
-      expect(described_class.call(2, 1)).to be(false)
-    end
-
-    it "returns false when value evaluates to nil" do
-      expect(described_class.call(nil, 1)).to be(false)
-      expect(described_class.call(1, nil)).to be(false)
-    end
-
-    it "raises ArgumentError with no arguments" do
-      expect { described_class.call }.to raise_error(ArgumentError)
-    end
-
-    it "raises ArgumentError with one argument" do
-      expect { described_class.call(10) }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/less_than_spec.rb b/spec/flipper/expressions/less_than_spec.rb
deleted file mode 100644
index 414c0eaea..000000000
--- a/spec/flipper/expressions/less_than_spec.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-RSpec.describe Flipper::Expressions::LessThan do
-  describe "#call" do
-    it "returns false when equal" do
-      expect(described_class.call(2, 2)).to be(false)
-    end
-
-    it "returns true when less" do
-      expect(described_class.call(1, 2)).to be(true)
-    end
-
-    it "returns true when less with args that need evaluation" do
-      expect(described_class.call(1, 2)).to be(true)
-    end
-
-    it "returns false when greater" do
-      expect(described_class.call(2, 1)).to be(false)
-    end
-
-    it "returns false when value evaluates to nil" do
-      expect(described_class.call(nil, 1)).to be(false)
-      expect(described_class.call(1, nil)).to be(false)
-    end
-
-    it "raises ArgumentError with no arguments" do
-      expect { described_class.call }.to raise_error(ArgumentError)
-    end
-
-    it "raises ArgumentError with one argument" do
-      expect { described_class.call(10) }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/not_equal_spec.rb b/spec/flipper/expressions/not_equal_spec.rb
deleted file mode 100644
index 91d8584ba..000000000
--- a/spec/flipper/expressions/not_equal_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-RSpec.describe Flipper::Expressions::NotEqual do
-  describe "#call" do
-    it "returns true when not equal" do
-      expect(described_class.call("basic", "plus")).to be(true)
-    end
-
-    it "returns false when equal" do
-      expect(described_class.call("basic", "basic")).to be(false)
-    end
-
-    it "raises ArgumentError for more arguments" do
-      expect { described_class.call(20, 10, 20).evaluate }.to raise_error(ArgumentError)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/now_spec.rb b/spec/flipper/expressions/now_spec.rb
deleted file mode 100644
index 95868f2bd..000000000
--- a/spec/flipper/expressions/now_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-RSpec.describe Flipper::Expressions::Now do
-  describe "#call" do
-    it "returns current time" do
-      expect(described_class.call).to be_within(2).of(Time.now.utc)
-    end
-
-    it "defaults to UTC" do
-      expect(described_class.call.zone).to eq("UTC")
-    end
-  end
-end
diff --git a/spec/flipper/expressions/number_spec.rb b/spec/flipper/expressions/number_spec.rb
deleted file mode 100644
index 003e61cc9..000000000
--- a/spec/flipper/expressions/number_spec.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-RSpec.describe Flipper::Expressions::Number do
-  describe "#call" do
-    it "returns Integer for Integer" do
-      expect(described_class.call(10)).to be(10)
-    end
-
-    it "returns Float for Float" do
-      expect(described_class.call(10.1)).to be(10.1)
-      expect(described_class.call(10.0)).to be(10.0)
-    end
-
-    it "returns Integer for String" do
-      expect(described_class.call('10')).to be(10)
-    end
-
-    it "returns Float for String" do
-      expect(described_class.call('10.0')).to be(10.0)
-      expect(described_class.call('10.1')).to be(10.1)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/percentage_of_actors_spec.rb b/spec/flipper/expressions/percentage_of_actors_spec.rb
deleted file mode 100644
index 180a4b881..000000000
--- a/spec/flipper/expressions/percentage_of_actors_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-RSpec.describe Flipper::Expressions::PercentageOfActors do
-  describe "#call" do
-    it "returns true when string in percentage enabled" do
-      expect(described_class.call("User;1", 42)).to be(true)
-    end
-
-    it "returns true when string in fractional percentage enabled" do
-      expect(described_class.call("User;1", 41.687)).to be(true)
-    end
-
-    it "returns false when string in percentage enabled" do
-      expect(described_class.call("User;1", 0)).to be(false)
-    end
-
-    it "changes value based on feature_name so not all actors get all features first" do
-      expect(described_class.call("User;1", 70, context: {feature_name: "a"})).to be(true)
-      expect(described_class.call("User;1", 70, context: {feature_name: "b"})).to be(false)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/percentage_spec.rb b/spec/flipper/expressions/percentage_spec.rb
deleted file mode 100644
index 1b31347b5..000000000
--- a/spec/flipper/expressions/percentage_spec.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-RSpec.describe Flipper::Expressions::Percentage do
-  describe "#call" do
-    it "returns numeric" do
-      expect(described_class.call(10)).to be(10.0)
-    end
-
-    it "returns 0 if less than 0" do
-      expect(described_class.call(-1)).to be(0)
-    end
-
-    it "returns 100 if greater than 100" do
-      expect(described_class.call(101)).to be(100)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/property_spec.rb b/spec/flipper/expressions/property_spec.rb
deleted file mode 100644
index 3d168f215..000000000
--- a/spec/flipper/expressions/property_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-RSpec.describe Flipper::Expressions::Property do
-  describe "#call" do
-    it "returns value for property key" do
-      context = { properties: { "flipper_id" => "User;1" } }
-      expect(described_class.call("flipper_id", context: context)).to eq("User;1")
-    end
-
-    it "returns nil if key not found in properties" do
-      context = { properties: { } }
-      expect(described_class.call("flipper_id", context: context)).to be(nil)
-    end
-  end
-end
diff --git a/spec/flipper/expressions/random_spec.rb b/spec/flipper/expressions/random_spec.rb
deleted file mode 100644
index 708f0f716..000000000
--- a/spec/flipper/expressions/random_spec.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-RSpec.describe Flipper::Expressions::Random do
-  describe "#call" do
-    it "returns random number based on max" do
-      100.times do
-        expect(described_class.call(10)).to be_between(0, 10)
-      end
-    end
-  end
-end
diff --git a/spec/flipper/expressions/string_spec.rb b/spec/flipper/expressions/string_spec.rb
deleted file mode 100644
index 9107e33fd..000000000
--- a/spec/flipper/expressions/string_spec.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-RSpec.describe Flipper::Expressions::String do
-  describe "#call" do
-    it "returns String for Numeric" do
-      expect(described_class.call(10)).to eq("10")
-    end
-
-    it "returns String" do
-      expect(described_class.call("test")).to eq("test")
-    end
-  end
-end
diff --git a/spec/flipper/expressions/time_spec.rb b/spec/flipper/expressions/time_spec.rb
deleted file mode 100644
index 55674cd08..000000000
--- a/spec/flipper/expressions/time_spec.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-RSpec.describe Flipper::Expressions::Time do
-  let(:time) { Time.now.round }
-
-  describe "#call" do
-    it "returns time for #to_s format" do
-      expect(described_class.call(time.to_s)).to eq(time)
-    end
-
-    it "returns time for #iso8601 format" do
-      expect(described_class.call(time.iso8601)).to eq(time)
-    end
-  end
-end
diff --git a/spec/flipper/gates/expression_spec.rb b/spec/flipper/gates/expression_spec.rb
index 21509d2d7..74361bba7 100644
--- a/spec/flipper/gates/expression_spec.rb
+++ b/spec/flipper/gates/expression_spec.rb
@@ -83,6 +83,11 @@ def context(expression, properties: {})
       expect(subject.protects?(expression)).to be(true)
     end
 
+    it 'returns true for Flipper::Constant' do
+      expression = Flipper.boolean(true)
+      expect(subject.protects?(expression)).to be(true)
+    end
+
     it 'returns true for Hash' do
       expression = Flipper.number(20).eq(20)
       expect(subject.protects?(expression.value)).to be(true)