diff --git a/pip_audit/__init__.py b/pip_audit/__init__.py
index a83f0e32..cca904ca 100644
--- a/pip_audit/__init__.py
+++ b/pip_audit/__init__.py
@@ -2,4 +2,6 @@
 The `pip_audit` APIs.
 """
 
-from pip_audit._version import __version__  # noqa: F401
+from pip_audit._version import __version__
+
+__all__ = ["__version__"]
diff --git a/pip_audit/_dependency_source/__init__.py b/pip_audit/_dependency_source/__init__.py
index 37f55568..66c8cd05 100644
--- a/pip_audit/_dependency_source/__init__.py
+++ b/pip_audit/_dependency_source/__init__.py
@@ -2,12 +2,23 @@
 Dependency source interfaces and implementations for `pip-audit`.
 """
 
-from .interface import (  # noqa: F401
+from .interface import (
     DependencyResolver,
     DependencyResolverError,
     DependencySource,
     DependencySourceError,
 )
-from .pip import PipSource, PipSourceError  # noqa: F401
-from .requirement import RequirementSource  # noqa: F401
-from .resolvelib import ResolveLibResolver  # noqa: F401
+from .pip import PipSource, PipSourceError
+from .requirement import RequirementSource
+from .resolvelib import ResolveLibResolver
+
+__all__ = [
+    "DependencyResolver",
+    "DependencyResolverError",
+    "DependencySource",
+    "DependencySourceError",
+    "PipSource",
+    "PipSourceError",
+    "RequirementSource",
+    "ResolveLibResolver",
+]
diff --git a/pip_audit/_dependency_source/resolvelib/__init__.py b/pip_audit/_dependency_source/resolvelib/__init__.py
index afda288a..f4f4bf84 100644
--- a/pip_audit/_dependency_source/resolvelib/__init__.py
+++ b/pip_audit/_dependency_source/resolvelib/__init__.py
@@ -2,4 +2,9 @@
 `resolvelib` interactions for `pip-audit`.
 """
 
-from .resolvelib import ResolveLibResolver, ResolveLibResolverError  # noqa: F401
+from .resolvelib import ResolveLibResolver, ResolveLibResolverError
+
+__all__ = [
+    "ResolveLibResolver",
+    "ResolveLibResolverError",
+]
diff --git a/pip_audit/_format/__init__.py b/pip_audit/_format/__init__.py
index f957c77e..1073672d 100644
--- a/pip_audit/_format/__init__.py
+++ b/pip_audit/_format/__init__.py
@@ -2,7 +2,14 @@
 Output format interfaces and implementations for `pip-audit`.
 """
 
-from .columns import ColumnsFormat  # noqa: F401
-from .cyclonedx import CycloneDxFormat  # noqa: F401
-from .interface import VulnerabilityFormat  # noqa: F401
-from .json import JsonFormat  # noqa: F401
+from .columns import ColumnsFormat
+from .cyclonedx import CycloneDxFormat
+from .interface import VulnerabilityFormat
+from .json import JsonFormat
+
+__all__ = [
+    "ColumnsFormat",
+    "CycloneDxFormat",
+    "VulnerabilityFormat",
+    "JsonFormat",
+]
diff --git a/pip_audit/_service/__init__.py b/pip_audit/_service/__init__.py
index 26216de1..03f2e217 100644
--- a/pip_audit/_service/__init__.py
+++ b/pip_audit/_service/__init__.py
@@ -2,7 +2,7 @@
 Vulnerability service interfaces and implementations for `pip-audit`.
 """
 
-from .interface import (  # noqa: F401
+from .interface import (
     Dependency,
     ResolvedDependency,
     ServiceError,
@@ -10,5 +10,16 @@
     VulnerabilityResult,
     VulnerabilityService,
 )
-from .osv import OsvService  # noqa: F401
-from .pypi import PyPIService  # noqa: F401
+from .osv import OsvService
+from .pypi import PyPIService
+
+__all__ = [
+    "Dependency",
+    "ResolvedDependency",
+    "ServiceError",
+    "SkippedDependency",
+    "VulnerabilityResult",
+    "VulnerabilityService",
+    "OsvService",
+    "PyPIService",
+]