diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 301906e5..3642e2cc 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -36,12 +36,3 @@ jobs:
     - name: Run test
       run: bundle exec rake test
       timeout-minutes: 5 # _should_ finish in under a minute
-
-    - uses: joshmfrankel/simplecov-check-action@main
-      if: ${{ matrix.os == 'ubuntu-latest' && github.event_name != 'pull_request' &&
-        !startsWith(matrix.ruby, 'truffleruby') && !startsWith(matrix.ruby, 'jruby') }}
-      with:
-        check_job_name: "SimpleCov - ${{ matrix.ruby }}"
-        minimum_suite_coverage: 90
-        minimum_file_coverage: 40 # TODO: increase this after switching to SASL::AuthenticationExchange
-        github_token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.simplecov b/.simplecov
new file mode 100644
index 00000000..3b249850
--- /dev/null
+++ b/.simplecov
@@ -0,0 +1,97 @@
+SimpleCov.formatters = [
+  SimpleCov::Formatter::HTMLFormatter,
+  SimpleCov::Formatter::JSONFormatter,
+]
+
+SimpleCov.configure do
+  command_name "Net::IMAP tests"
+  enable_coverage  :branch
+  enable_coverage  :method
+  enable_coverage  :eval
+  primary_coverage :branch
+
+  skip "/test/"
+  skip "/rakelib/"
+  cover "lib/**/*.rb"
+
+  group "Parser",     %w[lib/net/imap/response_parser.rb
+                           lib/net/imap/response_parser]
+
+  group "Client",     %w[lib/net/imap.rb
+                           lib/net/imap/connection_state.rb
+                           lib/net/imap/deprecated_client_options.rb
+                           lib/net/imap/errors.rb
+                           lib/net/imap/response_reader.rb]
+
+  group "Config",     %w[lib/net/imap/config.rb
+                           lib/net/imap/config]
+
+  group "Data Types", %w[lib/net/imap/flags.rb
+                           lib/net/imap/sequence_set.rb] +
+                           [%r{lib/net/imap/\w*_data\.rb},
+                            %r{lib/net/imap/\w*_result.rb},
+                            %r{lib/net/imap/data_\w+\.rb}]
+
+  group "SASL",       %w[lib/net/imap/sasl.rb
+                           lib/net/imap/sasl
+                           lib/net/imap/sasl_adapter.rb
+                           lib/net/imap/authenticators.rb]
+
+  group "StringPrep", %w[lib/net/imap/stringprep.rb
+                           lib/net/imap/stringprep]
+
+  if ENV.fetch("SIMPLECOV_DISABLE_MINIMUM_COVERAGE", "") == ""
+    coverage(:line) do
+      minimum           95
+
+      minimum_per_group 98, only: "Config"
+      minimum_per_group 97, only: "StringPrep"
+      minimum_per_group 97, only: "SASL"
+      minimum_per_group 95, only: "Data Types"
+      minimum_per_group 94, only: "Parser"
+      minimum_per_group 92, only: "Client"
+
+      minimum_per_file  90
+      minimum_per_file  87, only: "lib/net/imap/sasl/authenticators.rb"
+      minimum_per_file  86, only: "lib/net/imap/config/attr_type_coercion.rb"
+      minimum_per_file  84, only: "lib/net/imap/authenticators.rb"
+      minimum_per_file  80, only: "lib/net/imap/response_data.rb"
+      minimum_per_file  55, only: "lib/net/imap/search_result.rb"
+    end
+
+    coverage(:branch) do
+      minimum           80
+
+      minimum_per_group 92, only: "Data Types"
+      minimum_per_group 87, only: "Config"
+      minimum_per_group 83, only: "Client"
+      minimum_per_group 81, only: "Parser"
+      minimum_per_group 76, only: "SASL"
+      minimum_per_group 73, only: "StringPrep"
+
+      minimum_per_file  65
+      minimum_per_file  62, only: "lib/net/imap/sasl/scram_authenticator.rb"
+      minimum_per_file  50, only: "lib/net/imap/sasl/authenticators.rb"
+      minimum_per_file  50, only: "lib/net/imap/config/attr_accessors.rb"
+    end
+
+    coverage(:method) do
+      minimum            88
+
+      minimum_per_group 100, only: "Config"
+      minimum_per_group  92, only: "Data Types"
+      minimum_per_group  90, only: "StringPrep"
+      minimum_per_group  88, only: "Client"
+      minimum_per_group  83, only: "Parser"
+      minimum_per_group  82, only: "SASL"
+
+      minimum_per_file   66
+      minimum_per_file   64, only: "lib/net/imap/response_parser/parser_utils.rb"
+      minimum_per_file   57, only: "lib/net/imap/sasl/authenticators.rb"
+      minimum_per_file   50, only: "lib/net/imap/authenticators.rb"
+      minimum_per_file   50, only: "lib/net/imap/sasl/anonymous_authenticator.rb"
+      minimum_per_file   36, only: "lib/net/imap/sasl/protocol_adapters.rb"
+      minimum_per_file   20, only: "lib/net/imap/response_data.rb"
+    end
+  end
+end
diff --git a/test/lib/helper.rb b/test/lib/helper.rb
index 0977b2e8..cbbcef18 100644
--- a/test/lib/helper.rb
+++ b/test/lib/helper.rb
@@ -1,32 +1,7 @@
 if !(ENV["SIMPLECOV_DISABLE"] in /\A(1|y(es)?|t(rue)?)\z/i) &&
     RUBY_ENGINE == "ruby" # C Ruby only
-
   require "simplecov"
-
-  SimpleCov.formatters = [
-    SimpleCov::Formatter::HTMLFormatter,
-    SimpleCov::Formatter::JSONFormatter,
-  ]
-
-  SimpleCov.start do
-    command_name "Net::IMAP tests"
-    enable_coverage  :branch
-    primary_coverage :branch
-    enable_coverage_for_eval
-
-    add_filter "/test/"
-    add_filter "/rakelib/"
-
-    add_group "Parser", %w[lib/net/imap/response_parser.rb
-                          lib/net/imap/response_parser]
-    add_group "Config", %w[lib/net/imap/config.rb
-                          lib/net/imap/config]
-    add_group "SASL", %w[lib/net/imap/sasl.rb
-                        lib/net/imap/sasl
-                        lib/net/imap/authenticators.rb]
-    add_group "StringPrep", %w[lib/net/imap/stringprep.rb
-                              lib/net/imap/stringprep]
-  end
+  SimpleCov.start
 end
 
 require "test/unit"