diff --git a/plugins/brain/__init__.py b/plugins/brain/__init__.py
index 2c9689fd..6cfee0e8 100644
--- a/plugins/brain/__init__.py
+++ b/plugins/brain/__init__.py
@@ -560,7 +560,7 @@ def get_parameters(self, ctx, inputs):
             view=metric_choices,
         )
 
-        inputs.str(
+        inputs.int(
             "replication_factor",
             label="Replication factor",
             description=(
@@ -741,7 +741,6 @@ def get_parameters(self, ctx, inputs):
         inputs.str(
             "index_name",
             label="Index name",
-            required=True,
             description=(
                 "An optional name of a MongoDB vector search index to use or "
                 "create"
@@ -2688,6 +2687,8 @@ def _inject_brain_secrets(ctx):
         if key.startswith("FIFTYONE_BRAIN_SIMILARITY_"):
             _key = key[len("FIFTYONE_BRAIN_SIMILARITY_") :].lower()
             _backend, _key = _key.split("_", 1)
+            if _backend not in fob.brain_config.similarity_backends:
+                fob.brain_config.similarity_backends[_backend] = {}
             fob.brain_config.similarity_backends[_backend][_key] = value
 
 
diff --git a/plugins/brain/fiftyone.yml b/plugins/brain/fiftyone.yml
index 8a1289ea..076680af 100644
--- a/plugins/brain/fiftyone.yml
+++ b/plugins/brain/fiftyone.yml
@@ -1,6 +1,6 @@
 name: "@voxel51/brain"
 description: Utilities for working with the FiftyOne Brain
-version: 1.3.0
+version: 1.3.1
 fiftyone:
   version: ">=0.22"
 url: https://github.com/voxel51/fiftyone-plugins/tree/main/plugins/brain
diff --git a/plugins/zoo/__init__.py b/plugins/zoo/__init__.py
index 8aa5b44a..fca32681 100644
--- a/plugins/zoo/__init__.py
+++ b/plugins/zoo/__init__.py
@@ -743,6 +743,8 @@ def _inject_brain_secrets(ctx):
         if key.startswith("FIFTYONE_BRAIN_SIMILARITY_"):
             _key = key[len("FIFTYONE_BRAIN_SIMILARITY_") :].lower()
             _backend, _key = _key.split("_", 1)
+            if _backend not in fob.brain_config.similarity_backends:
+                fob.brain_config.similarity_backends[_backend] = {}
             fob.brain_config.similarity_backends[_backend][_key] = value
 
 
diff --git a/plugins/zoo/fiftyone.yml b/plugins/zoo/fiftyone.yml
index 901080fa..0592b682 100644
--- a/plugins/zoo/fiftyone.yml
+++ b/plugins/zoo/fiftyone.yml
@@ -1,6 +1,6 @@
 name: "@voxel51/zoo"
 description: A collection of FiftyOne Zoo utilities
-version: 1.3.1
+version: 1.3.2
 fiftyone:
   version: ">=0.22"
 url: https://github.com/voxel51/fiftyone-plugins/tree/main/plugins/zoo