diff --git a/python/lib/dependabot/python/file_parser/subdependency_type_parser.rb b/python/lib/dependabot/python/file_parser/subdependency_type_parser.rb
new file mode 100644
index 00000000000..20dcf2b9010
--- /dev/null
+++ b/python/lib/dependabot/python/file_parser/subdependency_type_parser.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require "toml-rb"
+require "dependabot/python/file_parser"
+require "dependabot/python/name_normaliser"
+
+module Dependabot
+  module Python
+    class FileParser
+      class PoetrySubdependencyTypeParser
+        def initialize(lockfile:)
+          @lockfile = lockfile
+        end
+
+        def subdep_type(dep)
+          category =
+            TomlRB.parse(lockfile.content).fetch("package", []).
+            find { |dets| normalise(dets.fetch("name")) == dep.name }.
+            fetch("category")
+
+          category == "dev" ? "dev-dependencies" : "dependencies"
+        end
+
+        private
+
+        attr_reader :lockfile
+
+        def normalise(name)
+          NameNormaliser.normalise(name)
+        end
+      end
+    end
+  end
+end
diff --git a/python/lib/dependabot/python/file_updater/poetry_file_updater.rb b/python/lib/dependabot/python/file_updater/poetry_file_updater.rb
index f88ddd3adcd..e674273961a 100644
--- a/python/lib/dependabot/python/file_updater/poetry_file_updater.rb
+++ b/python/lib/dependabot/python/file_updater/poetry_file_updater.rb
@@ -8,6 +8,7 @@
 require "dependabot/python/version"
 require "dependabot/python/requirement"
 require "dependabot/python/file_parser/python_requirement_parser"
+require "dependabot/python/file_parser/subdependency_type_parser"
 require "dependabot/python/file_updater"
 require "dependabot/python/native_helpers"
 require "dependabot/python/name_normaliser"
@@ -156,17 +157,10 @@ def lock_declaration_to_new_version!(poetry_object, dep)
         end
 
         def create_declaration_at_new_version!(poetry_object, dep)
-          poetry_object[subdep_type] ||= {}
-          poetry_object[subdep_type][dependency.name] = dep.version
-        end
+          subdep_type = subdependency_type_parser.subdep_type(dep)
 
-        def subdep_type
-          category =
-            TomlRB.parse(lockfile.content).fetch("package", []).
-            find { |dets| normalise(dets.fetch("name")) == dependency.name }.
-            fetch("category")
-
-          category == "dev" ? "dev-dependencies" : "dependencies"
+          poetry_object[subdep_type] ||= {}
+          poetry_object[subdep_type][dep.name] = dep.version
         end
 
         def sanitize(pyproject_content)
@@ -299,6 +293,13 @@ def python_requirement_parser
             )
         end
 
+        def subdependency_type_parser
+          @subdependency_type_parser ||=
+            FileParser::PoetrySubdependencyTypeParser.new(
+              lockfile: lockfile
+            )
+        end
+
         def language_version_manager
           @language_version_manager ||=
             LanguageVersionManager.new(
diff --git a/python/lib/dependabot/python/update_checker/poetry_version_resolver.rb b/python/lib/dependabot/python/update_checker/poetry_version_resolver.rb
index 43d28c8090b..e80562e7bdb 100644
--- a/python/lib/dependabot/python/update_checker/poetry_version_resolver.rb
+++ b/python/lib/dependabot/python/update_checker/poetry_version_resolver.rb
@@ -9,6 +9,7 @@
 require "dependabot/shared_helpers"
 require "dependabot/python/file_parser"
 require "dependabot/python/file_parser/python_requirement_parser"
+require "dependabot/python/file_parser/subdependency_type_parser"
 require "dependabot/python/file_updater/pyproject_preparer"
 require "dependabot/python/update_checker"
 require "dependabot/python/version"
@@ -275,6 +276,8 @@ def set_target_dependency_req(pyproject_content, updated_requirement)
 
           # If this is a sub-dependency, add the new requirement
           unless dependency.requirements.find { |r| r[:file] == pyproject.name }
+            subdep_type = subdependency_type_parser.subdep_type(dependency)
+
             poetry_object[subdep_type] ||= {}
             poetry_object[subdep_type][dependency.name] = updated_requirement
           end
@@ -294,15 +297,6 @@ def update_dependency_requirement(toml_node, requirement)
           end
         end
 
-        def subdep_type
-          category =
-            TomlRB.parse(lockfile.content).fetch("package", []).
-            find { |dets| normalise(dets.fetch("name")) == dependency.name }.
-            fetch("category")
-
-          category == "dev" ? "dev-dependencies" : "dependencies"
-        end
-
         def python_requirement_parser
           @python_requirement_parser ||=
             FileParser::PythonRequirementParser.new(
@@ -310,6 +304,13 @@ def python_requirement_parser
             )
         end
 
+        def subdependency_type_parser
+          @subdependency_type_parser ||=
+            FileParser::PoetrySubdependencyTypeParser.new(
+              lockfile: lockfile
+            )
+        end
+
         def language_version_manager
           @language_version_manager ||=
             LanguageVersionManager.new(