diff --git a/CHANGELOG.md b/CHANGELOG.md
index 763e3c91..6d3d61cf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog
 
+### 7.4.0
+* Warn when `KNAPSACK_PRO_*` environment variables are set manually if their values could be automatically determined from supported CI environments.
+
+  https://github.com/KnapsackPro/knapsack_pro-ruby/pull/254
+
+https://github.com/KnapsackPro/knapsack_pro-ruby/compare/v7.3.0...v7.4.0
+
 ### 7.3.0
 
 * [Queue Mode][RSpec] Pass each batch of tests to the queue hooks: `KnapsackPro::Hooks::Queue.before_subset_queue` and `KnapsackPro::Hooks::Queue.after_subset_queue`
diff --git a/lib/knapsack_pro/config/env.rb b/lib/knapsack_pro/config/env.rb
index eeeecb38..ce4fd33e 100644
--- a/lib/knapsack_pro/config/env.rb
+++ b/lib/knapsack_pro/config/env.rb
@@ -13,30 +13,21 @@ class Env
 
       class << self
         def ci_node_total
-          (ENV['KNAPSACK_PRO_CI_NODE_TOTAL'] ||
-            ci_env_for(:node_total) ||
-            1).to_i
+          (env_for('KNAPSACK_PRO_CI_NODE_TOTAL', :node_total) || 1).to_i
         end
 
         def ci_node_index
-          (ENV['KNAPSACK_PRO_CI_NODE_INDEX'] ||
-            ci_env_for(:node_index) ||
-            0).to_i
+          (env_for('KNAPSACK_PRO_CI_NODE_INDEX', :node_index) || 0).to_i
         end
 
         def ci_node_build_id
           env_name = 'KNAPSACK_PRO_CI_NODE_BUILD_ID'
-          ENV[env_name] ||
-            ci_env_for(:node_build_id) ||
+          env_for(env_name, :node_build_id) ||
             raise("Missing environment variable #{env_name}. Read more at #{KnapsackPro::Urls::KNAPSACK_PRO_CI_NODE_BUILD_ID}")
         end
 
         def ci_node_retry_count
-          (
-            ENV['KNAPSACK_PRO_CI_NODE_RETRY_COUNT'] ||
-            ci_env_for(:node_retry_count) ||
-            0
-          ).to_i
+          (env_for('KNAPSACK_PRO_CI_NODE_RETRY_COUNT', :node_retry_count) || 0).to_i
         end
 
         def max_request_retries
@@ -47,23 +38,19 @@ def max_request_retries
         end
 
         def commit_hash
-          ENV['KNAPSACK_PRO_COMMIT_HASH'] ||
-            ci_env_for(:commit_hash)
+          env_for('KNAPSACK_PRO_COMMIT_HASH', :commit_hash)
         end
 
         def branch
-          ENV['KNAPSACK_PRO_BRANCH'] ||
-            ci_env_for(:branch)
+          env_for('KNAPSACK_PRO_BRANCH', :branch)
         end
 
         def project_dir
-          ENV['KNAPSACK_PRO_PROJECT_DIR'] ||
-            ci_env_for(:project_dir)
+          env_for('KNAPSACK_PRO_PROJECT_DIR', :project_dir)
         end
 
         def user_seat
-          ENV['KNAPSACK_PRO_USER_SEAT'] ||
-            ci_env_for(:user_seat)
+          env_for('KNAPSACK_PRO_USER_SEAT', :user_seat)
         end
 
         def masked_user_seat
@@ -183,7 +170,7 @@ def fixed_test_suite_split?
         def fixed_queue_split
           @fixed_queue_split ||= begin
             env_name = 'KNAPSACK_PRO_FIXED_QUEUE_SPLIT'
-            computed = ENV.fetch(env_name, ci_env_for(:fixed_queue_split)).to_s
+            computed = env_for(env_name, :fixed_queue_split).to_s
 
             if !ENV.key?(env_name)
               KnapsackPro.logger.info("#{env_name} is not set. Using default value: #{computed}. Learn more at #{KnapsackPro::Urls::FIXED_QUEUE_SPLIT}")
@@ -249,10 +236,6 @@ def mode
           end
         end
 
-        def ci_env_for(env_name)
-          detected_ci.new.send(env_name)
-        end
-
         def detected_ci
           detected = KnapsackPro::Config::CI.constants.map do |constant|
             Object.const_get("KnapsackPro::Config::CI::#{constant}").new.detected
@@ -293,6 +276,21 @@ def ci?
         def required_env(env_name)
           ENV[env_name] || raise("Missing environment variable #{env_name}")
         end
+
+        def env_for(knapsack_env_name, ci_env_method)
+          knapsack_env_value = ENV[knapsack_env_name]
+          ci_env_value = ci_env_for(ci_env_method)
+
+          if !knapsack_env_value.nil? && !ci_env_value.nil? && knapsack_env_value != ci_env_value.to_s
+            KnapsackPro.logger.info("You have set the environment variable #{knapsack_env_name} to #{knapsack_env_value} which could be automatically determined from the CI environment as #{ci_env_value}.")
+          end
+
+          knapsack_env_value != nil ? knapsack_env_value : ci_env_value
+        end
+
+        def ci_env_for(env_name)
+          detected_ci.new.send(env_name)
+        end
       end
     end
   end
diff --git a/spec/knapsack_pro/config/env_spec.rb b/spec/knapsack_pro/config/env_spec.rb
index fc7028c7..8aabaa3e 100644
--- a/spec/knapsack_pro/config/env_spec.rb
+++ b/spec/knapsack_pro/config/env_spec.rb
@@ -17,6 +17,40 @@
 
         it { should eq 4 }
       end
+
+      context 'when both KNAPSACK_PRO_CI_NODE_TOTAL and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_CI_NODE_TOTAL' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:node_total).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '5' }
+          let(:ci_value) { 4 }
+
+          it { should eq 5 }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_CI_NODE_TOTAL to 5 which could be automatically determined from the CI environment as 4.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '5' }
+          let(:ci_value) { 5 }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -41,6 +75,40 @@
         it { should eq 2 }
       end
 
+      context 'when both KNAPSACK_PRO_CI_NODE_INDEX and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_CI_NODE_INDEX' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:node_index).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '3' }
+          let(:ci_value) { 2 }
+
+          it { should eq 3 }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_CI_NODE_INDEX to 3 which could be automatically determined from the CI environment as 2.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '3' }
+          let(:ci_value) { 3 }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
+
       context 'when order of loading envs does matter' do
         context 'when GitLab CI' do
           before { stub_const("ENV", { 'CI_NODE_INDEX' => '2', 'GITLAB_CI' => 'true' }) }
@@ -70,6 +138,40 @@
 
         it { should eq '8' }
       end
+
+      context 'when both KNAPSACK_PRO_CI_NODE_BUILD_ID and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_CI_NODE_BUILD_ID' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:node_build_id).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '7' }
+          let(:ci_value) { '8' }
+
+          it { should eq '7' }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_CI_NODE_BUILD_ID to 7 which could be automatically determined from the CI environment as 8.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '7' }
+          let(:ci_value) { '7' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV does not exist" do
@@ -95,6 +197,40 @@
 
         it { should eq 2 }
       end
+
+      context 'when both KNAPSACK_PRO_CI_NODE_RETRY_COUNT and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_CI_NODE_RETRY_COUNT' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:node_retry_count).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '1' }
+          let(:ci_value) { 2 }
+
+          it { should eq 1 }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_CI_NODE_RETRY_COUNT to 1 which could be automatically determined from the CI environment as 2.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '7' }
+          let(:ci_value) { '7' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -131,6 +267,40 @@
 
         it { should eq 'fe61a08118d0d52e97c38666eba1eaf3' }
       end
+
+      context 'when both KNAPSACK_PRO_COMMIT_HASH and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_COMMIT_HASH' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:commit_hash).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '3fa64859337f6e56409d49f865d13fd7' }
+          let(:ci_value) { 'fe61a08118d0d52e97c38666eba1eaf3' }
+
+          it { should eq '3fa64859337f6e56409d49f865d13fd7' }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_COMMIT_HASH to 3fa64859337f6e56409d49f865d13fd7 which could be automatically determined from the CI environment as fe61a08118d0d52e97c38666eba1eaf3.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '3fa64859337f6e56409d49f865d13fd7' }
+          let(:ci_value) { '3fa64859337f6e56409d49f865d13fd7' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -154,6 +324,40 @@
 
         it { should eq 'feature-branch' }
       end
+
+      context 'when both KNAPSACK_PRO_BRANCH and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_BRANCH' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:branch).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { 'master' }
+          let(:ci_value) { 'feature-branch' }
+
+          it { should eq 'master' }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_BRANCH to master which could be automatically determined from the CI environment as feature-branch.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { 'master' }
+          let(:ci_value) { 'master' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -177,6 +381,40 @@
 
         it { should eq '/home/runner/myapp' }
       end
+
+      context 'when both KNAPSACK_PRO_PROJECT_DIR and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_PROJECT_DIR' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:project_dir).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { '/home/user/myapp' }
+          let(:ci_value) { '/home/runner/myapp' }
+
+          it { should eq '/home/user/myapp' }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_PROJECT_DIR to /home/user/myapp which could be automatically determined from the CI environment as /home/runner/myapp.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { '/home/user/myapp' }
+          let(:ci_value) { '/home/user/myapp' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -200,6 +438,40 @@
 
         it { should eq 'Jane Doe' }
       end
+
+      context 'when both KNAPSACK_PRO_USER_SEAT and CI environment have value' do
+        let(:logger) { instance_double(Logger, info: nil) }
+
+        before do
+          stub_const("ENV", { 'KNAPSACK_PRO_USER_SEAT' => env_value })
+          expect(described_class).to receive(:ci_env_for).with(:user_seat).and_return(ci_value)
+          allow(KnapsackPro).to receive(:logger).and_return(logger)
+        end
+
+        context 'when values are different' do
+          let(:env_value) { 'John Doe' }
+          let(:ci_value) { 'Jane Doe' }
+
+          it { should eq 'John Doe' }
+
+          it 'logs a warning' do
+            expect(logger).to receive(:info).with(
+              'You have set the environment variable KNAPSACK_PRO_USER_SEAT to John Doe which could be automatically determined from the CI environment as Jane Doe.'
+            )
+            subject
+          end
+        end
+
+        context 'when values are the same' do
+          let(:env_value) { 'John Doe' }
+          let(:ci_value) { 'John Doe' }
+
+          it 'does not log a warning' do
+            expect(logger).not_to receive(:info)
+            subject
+          end
+        end
+      end
     end
 
     context "when ENV doesn't exist" do
@@ -345,7 +617,6 @@
     end
   end
 
-
   describe '.regular_mode?' do
     subject { described_class.regular_mode? }
 
@@ -630,26 +901,32 @@
     context 'when ENV exists' do
       context 'when KNAPSACK_PRO_FIXED_QUEUE_SPLIT=false' do
         [
-          ['AppVeyor', { 'APPVEYOR' => '123' }],
-          ['Buildkite', { 'BUILDKITE' => 'true' }],
-          ['CircleCI', { 'CIRCLECI' => 'true' }],
-          ['Cirrus CI', { 'CIRRUS_CI' => 'true' }],
-          ['Codefresh', { 'CF_BUILD_ID' => '123' }],
-          ['Codeship', { 'CI_NAME' => 'codeship' }],
-          ['GitHub Actions', { 'GITHUB_ACTIONS' => 'true' }],
-          ['GitLab CI', { 'GITLAB_CI' => 'true' }],
-          ['Heroku CI', { 'HEROKU_TEST_RUN_ID' => '123' }],
-          ['Semaphore CI 1.0', { 'SEMAPHORE_BUILD_NUMBER' => '123' }],
-          ['Semaphore CI 2.0', { 'SEMAPHORE' => 'true', 'SEMAPHORE_WORKFLOW_ID' => '123' }],
-          ['Travis CI', { 'TRAVIS' => 'true' }],
-          ['Unsupported CI', {}],
-        ].each do |ci, env|
+          ['AppVeyor', { 'APPVEYOR' => '123' }, false],
+          ['Buildkite', { 'BUILDKITE' => 'true' }, true],
+          ['CircleCI', { 'CIRCLECI' => 'true' }, false],
+          ['Cirrus CI', { 'CIRRUS_CI' => 'true' }, false],
+          ['Codefresh', { 'CF_BUILD_ID' => '123' }, false],
+          ['Codeship', { 'CI_NAME' => 'codeship' }, true],
+          ['GitHub Actions', { 'GITHUB_ACTIONS' => 'true' }, true],
+          ['GitLab CI', { 'GITLAB_CI' => 'true' }, true],
+          ['Heroku CI', { 'HEROKU_TEST_RUN_ID' => '123' }, false],
+          ['Semaphore CI 1.0', { 'SEMAPHORE_BUILD_NUMBER' => '123' }, false],
+          ['Semaphore CI 2.0', { 'SEMAPHORE' => 'true', 'SEMAPHORE_WORKFLOW_ID' => '123' }, false],
+          ['Travis CI', { 'TRAVIS' => 'true' }, true],
+          ['Unsupported CI', {}, true],
+        ].each do |ci, env, ci_env|
           it "on #{ci} it is false" do
+            stub_const("ENV", env.merge({ 'KNAPSACK_PRO_FIXED_QUEUE_SPLIT' => 'false' }))
+
             logger = instance_double(Logger)
             allow(KnapsackPro).to receive(:logger).and_return(logger)
-            expect(logger).not_to receive(:info)
-
-            stub_const("ENV", env.merge({ 'KNAPSACK_PRO_FIXED_QUEUE_SPLIT' => 'false' }))
+            if ci_env == false
+              expect(logger).not_to receive(:info)
+            else
+              expect(logger).to receive(:info).with(
+                'You have set the environment variable KNAPSACK_PRO_FIXED_QUEUE_SPLIT to false which could be automatically determined from the CI environment as true.'
+              )
+            end
 
             expect(subject).to eq(false)
           end
@@ -658,26 +935,32 @@
 
       context 'when KNAPSACK_PRO_FIXED_QUEUE_SPLIT=true' do
         [
-          ['AppVeyor', { 'APPVEYOR' => '123' }],
-          ['Buildkite', { 'BUILDKITE' => 'true' }],
-          ['CircleCI', { 'CIRCLECI' => 'true' }],
-          ['Cirrus CI', { 'CIRRUS_CI' => 'true' }],
-          ['Codefresh', { 'CF_BUILD_ID' => '123' }],
-          ['Codeship', { 'CI_NAME' => 'codeship' }],
-          ['GitHub Actions', { 'GITHUB_ACTIONS' => 'true' }],
-          ['GitLab CI', { 'GITLAB_CI' => 'true' }],
-          ['Heroku CI', { 'HEROKU_TEST_RUN_ID' => '123' }],
-          ['Semaphore CI 1.0', { 'SEMAPHORE_BUILD_NUMBER' => '123' }],
-          ['Semaphore CI 2.0', { 'SEMAPHORE' => 'true', 'SEMAPHORE_WORKFLOW_ID' => '123' }],
-          ['Travis CI', { 'TRAVIS' => 'true' }],
-          ['Unsupported CI', {}],
-        ].each do |ci, env|
+          ['AppVeyor', { 'APPVEYOR' => '123' }, false],
+          ['Buildkite', { 'BUILDKITE' => 'true' }, true],
+          ['CircleCI', { 'CIRCLECI' => 'true' }, false],
+          ['Cirrus CI', { 'CIRRUS_CI' => 'true' }, false],
+          ['Codefresh', { 'CF_BUILD_ID' => '123' }, false],
+          ['Codeship', { 'CI_NAME' => 'codeship' }, true],
+          ['GitHub Actions', { 'GITHUB_ACTIONS' => 'true' }, true],
+          ['GitLab CI', { 'GITLAB_CI' => 'true' }, true],
+          ['Heroku CI', { 'HEROKU_TEST_RUN_ID' => '123' }, false],
+          ['Semaphore CI 1.0', { 'SEMAPHORE_BUILD_NUMBER' => '123' }, false],
+          ['Semaphore CI 2.0', { 'SEMAPHORE' => 'true', 'SEMAPHORE_WORKFLOW_ID' => '123' }, false],
+          ['Travis CI', { 'TRAVIS' => 'true' }, true],
+          ['Unsupported CI', {}, true],
+        ].each do |ci, env, ci_env|
           it "on #{ci} it is true" do
+            stub_const("ENV", env.merge({ 'KNAPSACK_PRO_FIXED_QUEUE_SPLIT' => 'true' }))
+
             logger = instance_double(Logger)
             allow(KnapsackPro).to receive(:logger).and_return(logger)
-            expect(logger).not_to receive(:info)
-
-            stub_const("ENV", env.merge({ 'KNAPSACK_PRO_FIXED_QUEUE_SPLIT' => 'true' }))
+            if ci_env == true
+              expect(logger).not_to receive(:info)
+            else
+              expect(logger).to receive(:info).with(
+                'You have set the environment variable KNAPSACK_PRO_FIXED_QUEUE_SPLIT to true which could be automatically determined from the CI environment as false.'
+              )
+            end
 
             expect(subject).to eq(true)
           end
@@ -702,12 +985,12 @@
         ['Unsupported CI', {}, true],
       ].each do |ci, env, expected|
         it "on #{ci} it is #{expected}" do
+          stub_const("ENV", env)
+
           logger = instance_double(Logger)
           expect(KnapsackPro).to receive(:logger).and_return(logger)
           expect(logger).to receive(:info).with("KNAPSACK_PRO_FIXED_QUEUE_SPLIT is not set. Using default value: #{expected}. Learn more at #{KnapsackPro::Urls::FIXED_QUEUE_SPLIT}")
 
-          stub_const("ENV", env)
-
           expect(subject).to eq(expected)
         end
       end