diff --git a/.github/workflows/rspec_tests.yml b/.github/workflows/rspec_tests.yml
index 816fda8a8..dc106a34b 100644
--- a/.github/workflows/rspec_tests.yml
+++ b/.github/workflows/rspec_tests.yml
@@ -23,7 +23,7 @@ jobs:
       fail-fast: false
       matrix:
         ruby: ["3.1", "3.2", "3.3"]
-        gemfile: ["stripe_12", "stripe_13"]
+        gemfile: ["stripe_12", "stripe_13", "stripe_14", "stripe_15"]
     env:
       BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/${{ matrix.gemfile }}.gemfile
     steps:
diff --git a/Appraisals b/Appraisals
index 690909cd7..ff78e1117 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,3 +1,11 @@
+appraise "stripe-15" do
+  gem "stripe", "15.3.0"
+end
+
+appraise "stripe-14" do
+  gem "stripe", "14.0.0"
+end
+
 appraise "stripe-13" do
   gem "stripe", "13.4.0"
 end
diff --git a/gemfiles/stripe_12.gemfile.lock b/gemfiles/stripe_12.gemfile.lock
index 88b5215e0..5d77a7510 100644
--- a/gemfiles/stripe_12.gemfile.lock
+++ b/gemfiles/stripe_12.gemfile.lock
@@ -1,11 +1,11 @@
 PATH
   remote: ..
   specs:
-    stripe-ruby-mock (4.0.0)
+    stripe-ruby-mock (5.0.0)
       dante (>= 0.2.0)
       drb (>= 2.0.4, < 3)
       multi_json (~> 1.0)
-      stripe (> 5, < 14)
+      stripe (> 5, < 16)
 
 GEM
   remote: https://rubygems.org/
@@ -16,32 +16,32 @@ GEM
       thor (>= 0.14.0)
     daemons (1.4.1)
     dante (0.2.0)
-    diff-lcs (1.6.1)
-    dotenv (2.8.1)
-    drb (2.2.1)
+    diff-lcs (1.6.2)
+    dotenv (3.1.8)
+    drb (2.2.3)
     eventmachine (1.2.7)
-    multi_json (1.15.0)
-    rack (2.2.13)
-    rake (13.2.1)
-    rspec (3.13.0)
+    multi_json (1.17.0)
+    rack (2.2.20)
+    rake (13.3.0)
+    rspec (3.13.2)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
       rspec-mocks (~> 3.13.0)
-    rspec-core (3.13.3)
+    rspec-core (3.13.6)
       rspec-support (~> 3.13.0)
-    rspec-expectations (3.13.3)
+    rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-mocks (3.13.2)
+    rspec-mocks (3.13.6)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-support (3.13.2)
+    rspec-support (3.13.6)
     stripe (12.6.0)
     thin (1.8.2)
       daemons (~> 1.0, >= 1.0.9)
       eventmachine (~> 1.0, >= 1.0.4)
       rack (>= 1, < 3)
-    thor (1.3.2)
+    thor (1.4.0)
 
 PLATFORMS
   ruby
diff --git a/gemfiles/stripe_13.gemfile.lock b/gemfiles/stripe_13.gemfile.lock
index 8c3e4d4f1..e519e8955 100644
--- a/gemfiles/stripe_13.gemfile.lock
+++ b/gemfiles/stripe_13.gemfile.lock
@@ -1,11 +1,11 @@
 PATH
   remote: ..
   specs:
-    stripe-ruby-mock (4.0.0)
+    stripe-ruby-mock (5.0.0)
       dante (>= 0.2.0)
       drb (>= 2.0.4, < 3)
       multi_json (~> 1.0)
-      stripe (> 5, < 14)
+      stripe (> 5, < 16)
 
 GEM
   remote: https://rubygems.org/
@@ -16,32 +16,32 @@ GEM
       thor (>= 0.14.0)
     daemons (1.4.1)
     dante (0.2.0)
-    diff-lcs (1.6.1)
-    dotenv (2.8.1)
-    drb (2.2.1)
+    diff-lcs (1.6.2)
+    dotenv (3.1.8)
+    drb (2.2.3)
     eventmachine (1.2.7)
-    multi_json (1.15.0)
-    rack (2.2.13)
-    rake (13.2.1)
-    rspec (3.13.0)
+    multi_json (1.17.0)
+    rack (2.2.20)
+    rake (13.3.0)
+    rspec (3.13.2)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
       rspec-mocks (~> 3.13.0)
-    rspec-core (3.13.3)
+    rspec-core (3.13.6)
       rspec-support (~> 3.13.0)
-    rspec-expectations (3.13.3)
+    rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-mocks (3.13.2)
+    rspec-mocks (3.13.6)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
-    rspec-support (3.13.2)
+    rspec-support (3.13.6)
     stripe (13.4.0)
     thin (1.8.2)
       daemons (~> 1.0, >= 1.0.9)
       eventmachine (~> 1.0, >= 1.0.4)
       rack (>= 1, < 3)
-    thor (1.3.2)
+    thor (1.4.0)
 
 PLATFORMS
   ruby
diff --git a/gemfiles/stripe_14.gemfile b/gemfiles/stripe_14.gemfile
new file mode 100644
index 000000000..490aaff68
--- /dev/null
+++ b/gemfiles/stripe_14.gemfile
@@ -0,0 +1,13 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "appraisal"
+gem "stripe", "14.0.0"
+
+group :test do
+  gem "rake"
+  gem "dotenv"
+end
+
+gemspec path: "../"
diff --git a/gemfiles/stripe_14.gemfile.lock b/gemfiles/stripe_14.gemfile.lock
new file mode 100644
index 000000000..1a268001d
--- /dev/null
+++ b/gemfiles/stripe_14.gemfile.lock
@@ -0,0 +1,60 @@
+PATH
+  remote: ..
+  specs:
+    stripe-ruby-mock (5.0.0)
+      dante (>= 0.2.0)
+      drb (>= 2.0.4, < 3)
+      multi_json (~> 1.0)
+      stripe (> 5, < 16)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    appraisal (2.5.0)
+      bundler
+      rake
+      thor (>= 0.14.0)
+    daemons (1.4.1)
+    dante (0.2.0)
+    diff-lcs (1.6.2)
+    dotenv (3.1.8)
+    drb (2.2.3)
+    eventmachine (1.2.7)
+    multi_json (1.17.0)
+    rack (2.2.20)
+    rake (13.3.0)
+    rspec (3.13.2)
+      rspec-core (~> 3.13.0)
+      rspec-expectations (~> 3.13.0)
+      rspec-mocks (~> 3.13.0)
+    rspec-core (3.13.6)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-mocks (3.13.6)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-support (3.13.6)
+    stripe (14.0.0)
+    thin (1.8.2)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0, >= 1.0.4)
+      rack (>= 1, < 3)
+    thor (1.4.0)
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+  appraisal
+  dotenv
+  rake
+  rspec (~> 3.13.0)
+  stripe (= 14.0.0)
+  stripe-ruby-mock!
+  thin (~> 1.8.1)
+
+BUNDLED WITH
+   2.6.6
diff --git a/gemfiles/stripe_15.gemfile b/gemfiles/stripe_15.gemfile
new file mode 100644
index 000000000..dc2fdbc2f
--- /dev/null
+++ b/gemfiles/stripe_15.gemfile
@@ -0,0 +1,13 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "appraisal"
+gem "stripe", "15.3.0"
+
+group :test do
+  gem "rake"
+  gem "dotenv"
+end
+
+gemspec path: "../"
diff --git a/gemfiles/stripe_15.gemfile.lock b/gemfiles/stripe_15.gemfile.lock
new file mode 100644
index 000000000..6cc538d5e
--- /dev/null
+++ b/gemfiles/stripe_15.gemfile.lock
@@ -0,0 +1,60 @@
+PATH
+  remote: ..
+  specs:
+    stripe-ruby-mock (5.0.0)
+      dante (>= 0.2.0)
+      drb (>= 2.0.4, < 3)
+      multi_json (~> 1.0)
+      stripe (> 5, < 16)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    appraisal (2.5.0)
+      bundler
+      rake
+      thor (>= 0.14.0)
+    daemons (1.4.1)
+    dante (0.2.0)
+    diff-lcs (1.6.2)
+    dotenv (3.1.8)
+    drb (2.2.3)
+    eventmachine (1.2.7)
+    multi_json (1.17.0)
+    rack (2.2.20)
+    rake (13.3.0)
+    rspec (3.13.2)
+      rspec-core (~> 3.13.0)
+      rspec-expectations (~> 3.13.0)
+      rspec-mocks (~> 3.13.0)
+    rspec-core (3.13.6)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-mocks (3.13.6)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-support (3.13.6)
+    stripe (15.3.0)
+    thin (1.8.2)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0, >= 1.0.4)
+      rack (>= 1, < 3)
+    thor (1.4.0)
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+  appraisal
+  dotenv
+  rake
+  rspec (~> 3.13.0)
+  stripe (= 15.3.0)
+  stripe-ruby-mock!
+  thin (~> 1.8.1)
+
+BUNDLED WITH
+   2.6.6
diff --git a/spec/shared_stripe_examples/invoice_examples.rb b/spec/shared_stripe_examples/invoice_examples.rb
index afab6c43f..a5f39285f 100644
--- a/spec/shared_stripe_examples/invoice_examples.rb
+++ b/spec/shared_stripe_examples/invoice_examples.rb
@@ -210,7 +210,10 @@
     end
   end
 
-  context "retrieving upcoming invoice" do
+  # Note: Invoice.upcoming was removed in Stripe 14.0.0
+  # https://github.com/stripe/stripe-ruby/blob/master/CHANGELOG.md#1400---2025-04-01
+  # Use Invoice.create_preview instead
+  context "retrieving upcoming invoice", skip: (Gem::Version.new(Stripe::VERSION) >= Gem::Version.new('14.0.0')) do
     let(:customer)      { Stripe::Customer.create(source: stripe_helper.generate_card_token) }
     let(:coupon_amtoff) { stripe_helper.create_coupon(id: '100OFF', currency: 'usd', amount_off: 100_00, duration: 'repeating', duration_in_months: 6) }
     let(:coupon_pctoff) { stripe_helper.create_coupon(id: '50OFF', currency: 'usd', percent_off: 50, amount_off: nil, duration: 'repeating', duration_in_months: 6) }
diff --git a/spec/shared_stripe_examples/subscription_examples.rb b/spec/shared_stripe_examples/subscription_examples.rb
index 213aa26f0..360056426 100644
--- a/spec/shared_stripe_examples/subscription_examples.rb
+++ b/spec/shared_stripe_examples/subscription_examples.rb
@@ -586,7 +586,7 @@
         ]
       )
 
-      expect(subscription.current_period_end).to eq (Time.now + (7 * 60 * 60 * 24)).to_i
+      expect(subscription.current_period_end).to be_within(2).of((Time.now + (7 * 60 * 60 * 24)).to_i)
     end
 
     it 'sets current_period_end based on price month interval', live: true do
@@ -599,7 +599,7 @@
         ]
       )
 
-      expect(subscription.current_period_end).to eq (DateTime.now >> 1).to_time.to_i
+      expect(subscription.current_period_end).to be_within(2).of((DateTime.now >> 1).to_time.to_i)
     end
 
     it 'sets current_period_end based on price year interval', live: true do
@@ -612,7 +612,7 @@
         ]
       )
 
-      expect(subscription.current_period_end).to eq (DateTime.now >> 12).to_time.to_i
+      expect(subscription.current_period_end).to be_within(2).of((DateTime.now >> 12).to_time.to_i)
     end
 
     it 'add a new subscription to bill via an invoice' do
diff --git a/stripe-ruby-mock.gemspec b/stripe-ruby-mock.gemspec
index b212ec912..73ed9d200 100644
--- a/stripe-ruby-mock.gemspec
+++ b/stripe-ruby-mock.gemspec
@@ -22,7 +22,7 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ['lib']
 
-  gem.add_dependency 'stripe', '> 5', '< 14'
+  gem.add_dependency 'stripe', '> 5', '< 16'
   gem.add_dependency 'multi_json', '~> 1.0'
   gem.add_dependency 'dante', '>= 0.2.0'
   gem.add_dependency 'drb', '>= 2.0.4', '< 3'