diff --git a/stix2/registration.py b/stix2/registration.py
index bc07995..e3aa5e5 100644
--- a/stix2/registration.py
+++ b/stix2/registration.py
@@ -68,13 +68,11 @@ def _register_marking(new_marking, version=DEFAULT_VERSION):
             if not re.match(PREFIX_21_REGEX, prop_name):
                 raise ValueError("Property name '%s' must begin with an alpha character." % prop_name)
 
-    if version:
-        v = 'v' + version.replace('.', '')
-    else:
-        # Use default version (latest) if no version was provided.
-        v = 'v' + DEFAULT_VERSION.replace('.', '')
+    class_maps = registry.get_stix2_class_maps(
+        version or DEFAULT_VERSION
+    )
 
-    OBJ_MAP_MARKING = registry.STIX2_OBJ_MAPS[v]['markings']
+    OBJ_MAP_MARKING = class_maps['markings']
     if mark_type in OBJ_MAP_MARKING.keys():
         raise DuplicateRegistrationError("STIX Marking", mark_type)
     OBJ_MAP_MARKING[mark_type] = new_marking
@@ -130,13 +128,11 @@ def _register_observable(new_observable, version=DEFAULT_VERSION):
                     "is not a ListProperty containing ReferenceProperty." % prop_name,
                 )
 
-    if version:
-        v = 'v' + version.replace('.', '')
-    else:
-        # Use default version (latest) if no version was provided.
-        v = 'v' + DEFAULT_VERSION.replace('.', '')
+    class_maps = registry.get_stix2_class_maps(
+        version or DEFAULT_VERSION
+    )
 
-    OBJ_MAP_OBSERVABLE = registry.STIX2_OBJ_MAPS[v]['observables']
+    OBJ_MAP_OBSERVABLE = class_maps['observables']
     if new_observable._type in OBJ_MAP_OBSERVABLE.keys():
         raise DuplicateRegistrationError("Cyber Observable", new_observable._type)
     OBJ_MAP_OBSERVABLE[new_observable._type] = new_observable
@@ -182,8 +178,6 @@ def _register_observable_extension(
             if not re.match(PREFIX_21_REGEX, prop_name):
                 raise ValueError("Property name '%s' must begin with an alpha character." % prop_name)
 
-    v = 'v' + version.replace('.', '')
-
     try:
         observable_type = observable._type
     except AttributeError:
@@ -192,8 +186,9 @@ def _register_observable_extension(
             "created with the @CustomObservable decorator.",
         )
 
-    OBJ_MAP_OBSERVABLE = registry.STIX2_OBJ_MAPS[v]['observables']
-    EXT_MAP = registry.STIX2_OBJ_MAPS[v]['observable-extensions']
+    class_maps = registry.get_stix2_class_maps(version)
+    OBJ_MAP_OBSERVABLE = class_maps['observables']
+    EXT_MAP = class_maps['observable-extensions']
 
     try:
         if ext_type in EXT_MAP[observable_type].keys():
diff --git a/stix2/registry.py b/stix2/registry.py
index 6cb6cd8..692fe3e 100644
--- a/stix2/registry.py
+++ b/stix2/registry.py
@@ -26,3 +26,18 @@ def _collect_stix2_mappings():
             elif re.match(r'^stix2\.v2[0-9]\.common$', name) and is_pkg is False:
                 mod = importlib.import_module(name, str(top_level_module.__name__))
                 STIX2_OBJ_MAPS[ver]['markings'] = mod.OBJ_MAP_MARKING
+
+
+def get_stix2_class_maps(stix_version):
+    """
+    Get the stix2 class mappings for the given STIX version.
+
+    :param stix_version: A STIX version as a string
+    :return: The class mappings.  This will be a dict mapping from some general
+        category name, e.g. "object" to another mapping from STIX type
+        to a stix2 class.
+    """
+    stix_vid = "v" + stix_version.replace(".", "")
+    cls_maps = STIX2_OBJ_MAPS[stix_vid]
+
+    return cls_maps
diff --git a/stix2/utils.py b/stix2/utils.py
index 94921a7..76fbea0 100644
--- a/stix2/utils.py
+++ b/stix2/utils.py
@@ -340,21 +340,6 @@ def _stix_type_of(value):
     return type_
 
 
-def _get_stix2_class_maps(stix_version):
-    """
-    Get the stix2 class mappings for the given STIX version.
-
-    :param stix_version: A STIX version as a string
-    :return: The class mappings.  This will be a dict mapping from some general
-        category name, e.g. "object" to another mapping from STIX type
-        to a stix2 class.
-    """
-    stix_vid = "v" + stix_version.replace(".", "")
-    cls_maps = mappings.STIX2_OBJ_MAPS[stix_vid]
-
-    return cls_maps
-
-
 def is_sdo(value, stix_version=stix2.DEFAULT_VERSION):
     """
     Determine whether the given object, type, or ID is/is for an SDO.
@@ -369,7 +354,7 @@ def is_sdo(value, stix_version=stix2.DEFAULT_VERSION):
     # Eventually this needs to be moved into the stix2 library (and maybe
     # improved?); see cti-python-stix2 github issue #450.
 
-    cls_maps = _get_stix2_class_maps(stix_version)
+    cls_maps = mappings.get_stix2_class_maps(stix_version)
     type_ = _stix_type_of(value)
     result = type_ in cls_maps["objects"] and type_ not in {
         "relationship", "sighting", "marking-definition", "bundle",
@@ -389,7 +374,7 @@ def is_sco(value, stix_version=stix2.DEFAULT_VERSION):
     :return: True if the type of the given value is an SCO type; False
         if not
     """
-    cls_maps = _get_stix2_class_maps(stix_version)
+    cls_maps = mappings.get_stix2_class_maps(stix_version)
     type_ = _stix_type_of(value)
     result = type_ in cls_maps["observables"]
 
@@ -425,7 +410,7 @@ def is_object(value, stix_version=stix2.DEFAULT_VERSION):
     :return: True if the type of the given value is a valid STIX type with
         respect to the given STIX version; False if not
     """
-    cls_maps = _get_stix2_class_maps(stix_version)
+    cls_maps = mappings.get_stix2_class_maps(stix_version)
     type_ = _stix_type_of(value)
     result = type_ in cls_maps["observables"] or type_ in cls_maps["objects"]