diff --git a/pyproject.toml b/pyproject.toml
index d259ff60092..0b760a2b820 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -103,7 +103,7 @@ extend-exclude = [
     "tests/masonry/builders/fixtures/pep_561_stub_only*/*",
     "tests/utils/fixtures/setups/*",
 ]
-fix = true
+fix = false
 line-length = 88
 src = ["src"]
 target-version = "py38"
@@ -123,6 +123,7 @@ extend-select = [
     "TCH", # flake8-type-checking
     "TID", # flake8-tidy-imports
     "UP",  # pyupgrade
+    "PTH"
 ]
 ignore = [
     "B904", # use 'raise ... from err'
diff --git a/src/poetry/console/commands/check.py b/src/poetry/console/commands/check.py
index 1fe9cc550d7..756075f38e8 100644
--- a/src/poetry/console/commands/check.py
+++ b/src/poetry/console/commands/check.py
@@ -94,8 +94,8 @@ def _validate_readme(self, readme: str | list[str], poetry_file: Path) -> list[s
 
     def _validate_dependencies_source(self, config: dict[str, Any]) -> list[str]:
         """Check dependencies's source are valid"""
-        sources = {k["name"] for k in config.get("source", [])}
-        sources.add("pypi")
+        sources = {repository.name for repository in self.poetry.pool.all_repositories}
+        print(sources)
 
         dependency_declarations: list[
             dict[str, str | dict[str, str] | list[dict[str, str]]]
@@ -119,6 +119,8 @@ def _validate_dependencies_source(self, config: dict[str, Any]) -> list[str]:
                 elif isinstance(declaration, dict) and "source" in declaration:
                     all_referenced_sources.add(declaration["source"])
 
+        print(all_referenced_sources)
+
         return [
             f'Invalid source "{source}" referenced in dependencies.'
             for source in sorted(all_referenced_sources - sources)
diff --git a/tests/console/commands/test_check.py b/tests/console/commands/test_check.py
index 957683619a2..a400b55f94f 100644
--- a/tests/console/commands/test_check.py
+++ b/tests/console/commands/test_check.py
@@ -71,6 +71,7 @@ def test_check_valid(tester: CommandTester) -> None:
 def test_check_invalid(
     mocker: MockerFixture, tester: CommandTester, fixture_dir: FixtureDirGetter
 ) -> None:
+
     mocker.patch(
         "poetry.poetry.Poetry.file",
         return_value=TOMLFile(fixture_dir("invalid_pyproject") / "pyproject.toml"),