diff --git a/openstackclient/compute/client.py b/openstackclient/compute/client.py
index 23979ec7f3..74979bef36 100644
--- a/openstackclient/compute/client.py
+++ b/openstackclient/compute/client.py
@@ -11,7 +11,6 @@
 #   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #   License for the specific language governing permissions and limitations
 #   under the License.
-#
 
 import logging
 
@@ -21,13 +20,11 @@ from openstackclient.i18n import _
 
 LOG = logging.getLogger(__name__)
 
+# global variables used when building the shell
 DEFAULT_API_VERSION = '2.1'
 API_VERSION_OPTION = 'os_compute_api_version'
 API_NAME = 'compute'
-API_VERSIONS = {
-    '2': 'openstack.connection.Connection',
-    '2.1': 'openstack.connection.Connection',
-}
+API_VERSIONS = ('2', '2.1')
 
 
 def make_client(instance):
diff --git a/openstackclient/identity/client.py b/openstackclient/identity/client.py
index 013c599da0..707112cd05 100644
--- a/openstackclient/identity/client.py
+++ b/openstackclient/identity/client.py
@@ -11,7 +11,6 @@
 #   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #   License for the specific language governing permissions and limitations
 #   under the License.
-#
 
 import logging
 
@@ -20,9 +19,9 @@ from osc_lib import utils
 
 from openstackclient.i18n import _
 
-
 LOG = logging.getLogger(__name__)
 
+# global variables used when building the shell
 DEFAULT_API_VERSION = '3'
 API_VERSION_OPTION = 'os_identity_api_version'
 API_NAME = 'identity'
diff --git a/openstackclient/image/client.py b/openstackclient/image/client.py
index d5ee52b35e..69a08d82f2 100644
--- a/openstackclient/image/client.py
+++ b/openstackclient/image/client.py
@@ -11,7 +11,6 @@
 #   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #   License for the specific language governing permissions and limitations
 #   under the License.
-#
 
 import logging
 
@@ -21,13 +20,11 @@ from openstackclient.i18n import _
 
 LOG = logging.getLogger(__name__)
 
+# global variables used when building the shell
 DEFAULT_API_VERSION = '2'
 API_VERSION_OPTION = 'os_image_api_version'
 API_NAME = 'image'
-API_VERSIONS = {
-    '1': 'openstack.connection.Connection',
-    '2': 'openstack.connection.Connection',
-}
+API_VERSIONS = ('1', '2')
 
 
 def make_client(instance):
diff --git a/openstackclient/network/client.py b/openstackclient/network/client.py
index 1970ab7a85..faaa54e2b1 100644
--- a/openstackclient/network/client.py
+++ b/openstackclient/network/client.py
@@ -9,7 +9,6 @@
 #   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #   License for the specific language governing permissions and limitations
 #   under the License.
-#
 
 import logging
 
@@ -17,16 +16,13 @@ from osc_lib import utils
 
 from openstackclient.i18n import _
 
-
 LOG = logging.getLogger(__name__)
 
+# global variables used when building the shell
 DEFAULT_API_VERSION = '2.0'
 API_VERSION_OPTION = 'os_network_api_version'
-API_NAME = "network"
-API_VERSIONS = {
-    "2.0": "openstack.connection.Connection",
-    "2": "openstack.connection.Connection",
-}
+API_NAME = 'network'
+API_VERSIONS = ('2.0', '2')
 
 
 def make_client(instance):
diff --git a/openstackclient/object/client.py b/openstackclient/object/client.py
index 9eb7ad7baa..466f132ec2 100644
--- a/openstackclient/object/client.py
+++ b/openstackclient/object/client.py
@@ -19,12 +19,11 @@ from osc_lib import utils
 
 from openstackclient.api import object_store_v1
 
+# global variables used when building the shell
 DEFAULT_API_VERSION = '1'
 API_VERSION_OPTION = 'os_object_api_version'
 API_NAME = 'object_store'
-API_VERSIONS = {
-    '1': 'openstackclient.object.client.ObjectClientv1',
-}
+API_VERSIONS = ('1',)
 
 
 def make_client(instance):
diff --git a/openstackclient/shell.py b/openstackclient/shell.py
index df60d3c073..50a767ec35 100644
--- a/openstackclient/shell.py
+++ b/openstackclient/shell.py
@@ -88,17 +88,34 @@ class OpenStackShell(shell.OpenStackShell):
                     # this throws an exception if invalid
                     skip_old_check = mod_check_api_version(version_opt)
 
+                # NOTE(stephenfin): API_VERSIONS has traditionally been a
+                # dictionary but the values are only used internally and are
+                # ignored for the modules using SDK. So we now support tuples
+                # instead.
                 mod_versions = getattr(mod, 'API_VERSIONS', None)
-                if not skip_old_check and mod_versions:
+                if mod_versions is not None and not isinstance(
+                    mod_versions, (dict, tuple)
+                ):
+                    raise TypeError(
+                        f'Plugin {mod} has incompatible API_VERSIONS. '
+                        f'Expected: tuple, dict. Got: {type(mod_versions)}. '
+                        f'Please report this to your package maintainer.'
+                    )
+
+                if mod_versions and not skip_old_check:
                     if version_opt not in mod_versions:
                         sorted_versions = sorted(
-                            mod.API_VERSIONS.keys(),
+                            list(mod.API_VERSIONS),
                             key=lambda s: list(map(int, s.split('.'))),
                         )
                         self.log.warning(
-                            "{} version {} is not in supported versions: {}".format(
-                                api, version_opt, ', '.join(sorted_versions)
-                            )
+                            "%(name)s API version %(version)s is not in "
+                            "supported versions: %(supported)s",
+                            {
+                                'name': api,
+                                'version': version_opt,
+                                'supported': ', '.join(sorted_versions),
+                            },
                         )
 
                 # Command groups deal only with major versions