diff --git a/README.md b/README.md
index 77efafd..eefb770 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,7 @@ ActiveRecordDoctor::Rake::Task.new do |task|
   task.deps = []
 
   # A path to your active_record_doctor configuration file.
-  task.config_path = ::Rails.root.join(".active_record_doctor")
+  task.config_path = ::Rails.root.join(".active_record_doctor.rb")
 
   # A Proc called right before running detectors that should ensure your Active
   # Record models are preloaded and a database connection is ready.
@@ -111,7 +111,7 @@ If you want to use the default configuration then you don't have to do anything.
 Just run `active_record_doctor` in your project directory.
 
 If you want to customize the tool you should create a file named
-`.active_record_doctor` in your project root directory with content like:
+`.active_record_doctor.rb` in your project root directory with content like:
 
 ```ruby
 ActiveRecordDoctor.configure do
diff --git a/lib/active_record_doctor/rake/task.rb b/lib/active_record_doctor/rake/task.rb
index 57586a4..43c2f69 100644
--- a/lib/active_record_doctor/rake/task.rb
+++ b/lib/active_record_doctor/rake/task.rb
@@ -68,9 +68,41 @@ def runner
       end
 
       def config
-        @config ||= begin
-          path = config_path && File.exist?(config_path) ? config_path : nil
-          ActiveRecordDoctor.load_config_with_defaults(path)
+        @config ||=
+          ActiveRecordDoctor.load_config_with_defaults(effective_config_path)
+      end
+
+      def effective_config_path
+        if config_path.nil?
+          # No explicit config_path was set, so we're trying to use defaults.
+          legacy_default_path = Rails.root.join(".active_record_doctor")
+          new_default_path = Rails.root.join(".active_record_doctor.rb")
+
+          # First, if the legacy file exists we'll use it but show a warning.
+          if legacy_default_path.exist?
+            warn(<<~WARN.squish)
+              DEPRECATION WARNING: active_record_doctor is using the default
+              configuration file located in #{legacy_default_path.basename}. However,
+              that default will change to #{new_default_path.basename} in the future.
+
+              In order to avoid errors, please rename the file from
+              #{legacy_default_path.basename} to #{new_default_path.basename}.
+            WARN
+
+            return legacy_default_path
+          end
+
+          # Second, if the legacy file does NOT exist, but the new one does then
+          # we'll use that.
+          if new_default_path.exist?
+            return new_default_path
+          end
+
+          # Otherwise, there's no configuration file in use.
+          nil
+        else
+          # If an explicit configuration file was set then we use it as is.
+          config_path
         end
       end
 
diff --git a/lib/tasks/active_record_doctor.rake b/lib/tasks/active_record_doctor.rake
index c6925ab..e96cc7d 100644
--- a/lib/tasks/active_record_doctor.rake
+++ b/lib/tasks/active_record_doctor.rake
@@ -19,6 +19,5 @@ ActiveRecordDoctor::Rake::Task.new do |task|
   # This file is imported when active_record_doctor is being used as part of a
   # Rails app so it's the right place for all Rails-specific settings.
   task.deps = [:environment]
-  task.config_path = Rails.root.join(".active_record_doctor")
   task.setup = -> { Rails.application.eager_load! }
 end
diff --git a/test/setup.rb b/test/setup.rb
index c6c1550..4ede3e8 100644
--- a/test/setup.rb
+++ b/test/setup.rb
@@ -127,7 +127,7 @@ def config_file(content)
     @previous_dir = Dir.pwd
 
     directory = Dir.mktmpdir("active_record_doctor")
-    @config_path = File.join(directory, ".active_record_doctor")
+    @config_path = File.join(directory, ".active_record_doctor.rb")
     File.write(@config_path, content)
     Dir.chdir(directory)