diff --git a/hyperglass/main.py b/hyperglass/main.py
index 8d753ca..c01a16e 100644
--- a/hyperglass/main.py
+++ b/hyperglass/main.py
@@ -14,7 +14,12 @@ from gunicorn.glogging import Logger  # type: ignore
 
 # Local
 from .log import log, setup_lib_logging
-from .plugins import InputPluginManager, OutputPluginManager, register_plugin
+from .plugins import (
+    InputPluginManager,
+    OutputPluginManager,
+    register_plugin,
+    init_builtin_plugins,
+)
 from .constants import MIN_NODE_VERSION, MIN_PYTHON_VERSION, __version__
 from .util.frontend import get_node_version
 
@@ -123,6 +128,10 @@ def cache_config() -> bool:
 def register_all_plugins(devices: "Devices") -> None:
     """Validate and register configured plugins."""
 
+    # Register built-in plugins.
+    init_builtin_plugins()
+
+    # Register external plugins.
     for plugin_file, directives in devices.directive_plugins().items():
         failures = register_plugin(plugin_file, directives=directives)
         for failure in failures:
diff --git a/hyperglass/plugins/__init__.py b/hyperglass/plugins/__init__.py
index 1ca2d24..aa01a28 100644
--- a/hyperglass/plugins/__init__.py
+++ b/hyperglass/plugins/__init__.py
@@ -1,13 +1,13 @@
 """hyperglass Plugins."""
 
 # Local
-from .main import init_plugins, register_plugin
+from .main import register_plugin, init_builtin_plugins
 from ._input import InputPlugin, InputPluginReturn
 from ._output import OutputType, OutputPlugin
 from ._manager import InputPluginManager, OutputPluginManager
 
 __all__ = (
-    "init_plugins",
+    "init_builtin_plugins",
     "InputPlugin",
     "InputPluginManager",
     "InputPluginReturn",
diff --git a/hyperglass/plugins/main.py b/hyperglass/plugins/main.py
index aef1645..c71c7fc 100644
--- a/hyperglass/plugins/main.py
+++ b/hyperglass/plugins/main.py
@@ -20,7 +20,14 @@ _PLUGIN_GLOBALS = {"InputPlugin": InputPlugin, "OutputPlugin": OutputPlugin, "lo
 
 
 def _is_class(module: Any, obj: object) -> bool:
-    return isclass(obj) and obj.__module__ == module.__name__
+    if isclass(obj):
+        # Get the object's containing module name.
+        obj_module_name: str = getattr(obj, "__module__", "")
+        # Get the module's name.
+        module_name: str = getattr(module, "__name__", None)
+        # Only validate objects that are members of the module.
+        return module_name in obj_module_name
+    return False
 
 
 def _register_from_module(module: Any, **kwargs: Any) -> Tuple[str, ...]:
@@ -52,7 +59,7 @@ def _module_from_file(file: Path) -> Any:
     return module
 
 
-def init_plugins() -> None:
+def init_builtin_plugins() -> None:
     """Initialize all built-in plugins."""
     _register_from_module(_builtin)