diff --git a/stix2/datastore/relational_db/query.py b/stix2/datastore/relational_db/query.py
index 5cdf14cd..eb906759 100644
--- a/stix2/datastore/relational_db/query.py
+++ b/stix2/datastore/relational_db/query.py
@@ -7,6 +7,7 @@
 from stix2.datastore import DataSourceError
 from stix2.datastore.relational_db.utils import (
     canonicalize_table_name, schema_for, table_name_for,
+    see_through_workbench,
 )
 import stix2.properties
 import stix2.utils
@@ -68,6 +69,9 @@ def _stix2_class_for(stix_id):
         stix_type, stix_version=stix2.DEFAULT_VERSION,
     )
 
+    if stix_class:
+        stix_class = see_through_workbench(stix_class)
+
     return stix_class
 
 
diff --git a/stix2/datastore/relational_db/utils.py b/stix2/datastore/relational_db/utils.py
index 65257426..1b8a9345 100644
--- a/stix2/datastore/relational_db/utils.py
+++ b/stix2/datastore/relational_db/utils.py
@@ -7,6 +7,7 @@
     IntegerProperty, Property, ReferenceProperty, StringProperty,
     TimestampProperty,
 )
+import stix2.v21
 from stix2.v21.base import (
     _DomainObject, _Extension, _MetaObject, _Observable, _RelationshipObject,
 )
@@ -68,18 +69,38 @@ def get_all_subclasses(cls):
     return all_subclasses
 
 
+def see_through_workbench(cls):
+    """
+    Deal with the workbench patching the registry.  This takes the given
+    "class" as obtained from the registry, and tries to find a real type.
+    The workbench replaces real types with "partial" objects, which causes
+    errors if used in type-specific contexts, e.g. issubclass().
+
+    :param cls: A registry-obtained "class" value
+    :return: A real class value
+    """
+    if hasattr(cls, "args"):
+        # The partial object's one stored positional arg is a subclass
+        # of the class we need.  But it will do.
+        return cls.args[0]
+    else:
+        return cls
+
+
 def get_stix_object_classes():
-    yield from get_all_subclasses(_DomainObject)
-    yield from get_all_subclasses(_RelationshipObject)
-    yield from get_all_subclasses(_Observable)
-    yield from get_all_subclasses(_MetaObject)
-    # Non-object extensions (property or toplevel-property only)
-    for ext_cls in get_all_subclasses(_Extension):
-        if ext_cls.extension_type not in (
+    for type_, cls in stix2.v21.OBJ_MAP.items():
+        if type_ != "bundle":
+            yield see_through_workbench(cls)
+
+    # The workbench only patches SDO types, so we shouldn't have to do the
+    # same hackage with other kinds of types.
+    yield from stix2.v21.OBJ_MAP_OBSERVABLE.values()
+    yield from (
+        cls for cls in stix2.v21.EXT_MAP.values()
+        if cls.extension_type not in (
             "new-sdo", "new-sco", "new-sro",
-        ):
-            yield ext_cls
-
+        )
+    )
 
 def schema_for(stix_class):