diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 6b46767..ad56a78 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "4.9.0"
+  ".": "4.10.0"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3cf6528..5ad3131 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 4.10.0 (2026-03-26)
+
+Full Changelog: [v4.9.0...v4.10.0](https://github.com/runwayml/sdk-python/compare/v4.9.0...v4.10.0)
+
+### Features
+
+* **internal:** implement indices array format for query and form serialization ([d8fecc7](https://github.com/runwayml/sdk-python/commit/d8fecc71d2e6b940f06553a0ffa45b0372d7f8cf))
+
 ## 4.9.0 (2026-03-25)
 
 Full Changelog: [v4.8.0...v4.9.0](https://github.com/runwayml/sdk-python/compare/v4.8.0...v4.9.0)
diff --git a/pyproject.toml b/pyproject.toml
index 249574e..dcbf477 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "runwayml"
-version = "4.9.0"
+version = "4.10.0"
 description = "The official Python library for the runwayml API"
 dynamic = ["readme"]
 license = "Apache-2.0"
diff --git a/scripts/mock b/scripts/mock
index 09eb49f..290e21b 100755
--- a/scripts/mock
+++ b/scripts/mock
@@ -24,7 +24,7 @@ if [ "$1" == "--daemon" ]; then
   # Pre-install the package so the download doesn't eat into the startup timeout
   npm exec --package=@stdy/cli@0.19.7 -- steady --version
 
-  npm exec --package=@stdy/cli@0.19.7 -- steady --host 127.0.0.1 -p 4010 --validator-form-array-format=comma --validator-query-array-format=comma --validator-form-object-format=brackets --validator-query-object-format=brackets "$URL" &> .stdy.log &
+  npm exec --package=@stdy/cli@0.19.7 -- steady --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL" &> .stdy.log &
 
   # Wait for server to come online via health endpoint (max 30s)
   echo -n "Waiting for server"
@@ -48,5 +48,5 @@ if [ "$1" == "--daemon" ]; then
 
   echo
 else
-  npm exec --package=@stdy/cli@0.19.7 -- steady --host 127.0.0.1 -p 4010 --validator-form-array-format=comma --validator-query-array-format=comma --validator-form-object-format=brackets --validator-query-object-format=brackets "$URL"
+  npm exec --package=@stdy/cli@0.19.7 -- steady --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL"
 fi
diff --git a/scripts/test b/scripts/test
index e46b9b5..661f9bf 100755
--- a/scripts/test
+++ b/scripts/test
@@ -43,7 +43,7 @@ elif ! steady_is_running ; then
   echo -e "To run the server, pass in the path or url of your OpenAPI"
   echo -e "spec to the steady command:"
   echo
-  echo -e "  \$ ${YELLOW}npm exec --package=@stdy/cli@0.19.7 -- steady path/to/your.openapi.yml --host 127.0.0.1 -p 4010 --validator-form-array-format=comma --validator-query-array-format=comma --validator-form-object-format=brackets --validator-query-object-format=brackets${NC}"
+  echo -e "  \$ ${YELLOW}npm exec --package=@stdy/cli@0.19.7 -- steady path/to/your.openapi.yml --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets${NC}"
   echo
 
   exit 1
diff --git a/src/runwayml/_qs.py b/src/runwayml/_qs.py
index ada6fd3..de8c99b 100644
--- a/src/runwayml/_qs.py
+++ b/src/runwayml/_qs.py
@@ -101,7 +101,10 @@ def _stringify_item(
                     items.extend(self._stringify_item(key, item, opts))
                 return items
             elif array_format == "indices":
-                raise NotImplementedError("The array indices format is not supported yet")
+                items = []
+                for i, item in enumerate(value):
+                    items.extend(self._stringify_item(f"{key}[{i}]", item, opts))
+                return items
             elif array_format == "brackets":
                 items = []
                 key = key + "[]"
diff --git a/src/runwayml/_version.py b/src/runwayml/_version.py
index 4e4cfdc..1f2d85c 100644
--- a/src/runwayml/_version.py
+++ b/src/runwayml/_version.py
@@ -1,4 +1,4 @@
 # File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
 __title__ = "runwayml"
-__version__ = "4.9.0"  # x-release-please-version
+__version__ = "4.10.0"  # x-release-please-version