diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 048d674e..8cce2b69 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "9.12.0"
+  ".": "9.12.1"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5fcced97..2f021cd7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 9.12.1 (2026-06-16)
+
+Full Changelog: [v9.12.0...v9.12.1](https://github.com/Finch-API/finch-api-node/compare/v9.12.0...v9.12.1)
+
+### Bug Fixes
+
+* **client:** send content-type header for requests with an omitted optional body ([94c0b7f](https://github.com/Finch-API/finch-api-node/commit/94c0b7f440454ae4eff4a12dae821142f9c6e728))
+
 ## 9.12.0 (2026-06-09)
 
 Full Changelog: [v9.11.2...v9.12.0](https://github.com/Finch-API/finch-api-node/compare/v9.11.2...v9.12.0)
diff --git a/package.json b/package.json
index f3ba5cc7..0a7d2e53 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@tryfinch/finch-api",
-  "version": "9.12.0",
+  "version": "9.12.1",
   "description": "The official TypeScript library for the Finch API",
   "author": "Finch <founders@tryfinch.com>",
   "types": "dist/index.d.ts",
diff --git a/packages/mcp-server/manifest.json b/packages/mcp-server/manifest.json
index 9ef0c50d..10208de3 100644
--- a/packages/mcp-server/manifest.json
+++ b/packages/mcp-server/manifest.json
@@ -1,7 +1,7 @@
 {
   "dxt_version": "0.2",
   "name": "@tryfinch/finch-api-mcp",
-  "version": "9.12.0",
+  "version": "9.12.1",
   "description": "The official MCP Server for the Finch API",
   "author": {
     "name": "Finch",
diff --git a/packages/mcp-server/package.json b/packages/mcp-server/package.json
index f8d46e0c..c3b26972 100644
--- a/packages/mcp-server/package.json
+++ b/packages/mcp-server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@tryfinch/finch-api-mcp",
-  "version": "9.12.0",
+  "version": "9.12.1",
   "description": "The official MCP Server for the Finch API",
   "author": "Finch <founders@tryfinch.com>",
   "types": "dist/index.d.ts",
diff --git a/packages/mcp-server/src/server.ts b/packages/mcp-server/src/server.ts
index 30f27938..22f6e4aa 100644
--- a/packages/mcp-server/src/server.ts
+++ b/packages/mcp-server/src/server.ts
@@ -29,7 +29,7 @@ export const newMcpServer = async ({
   new McpServer(
     {
       name: 'tryfinch_finch_api_api',
-      version: '9.12.0',
+      version: '9.12.1',
     },
     {
       instructions: await getInstructions({ stainlessApiKey, customInstructionsPath }),
diff --git a/src/client.ts b/src/client.ts
index 9f962e54..a49b80ad 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -816,11 +816,19 @@ export class Finch {
     return () => controller.abort();
   }
 
-  private buildBody({ options: { body, headers: rawHeaders } }: { options: FinalRequestOptions }): {
+  private buildBody({ options }: { options: FinalRequestOptions }): {
     bodyHeaders: HeadersLike;
     body: BodyInit | undefined;
   } {
+    const { body, headers: rawHeaders } = options;
     if (!body) {
+      // A resource method always passes a `body` key when its operation defines a
+      // request body, even if the caller omitted an optional body param. Keep the
+      // content-type for those, and only elide it for operations with no body at
+      // all (e.g. GET/DELETE).
+      if (body == null && 'body' in options) {
+        return this.#encoder({ body, headers: buildHeaders([rawHeaders]) });
+      }
       return { bodyHeaders: undefined, body: undefined };
     }
     const headers = buildHeaders([rawHeaders]);
diff --git a/src/version.ts b/src/version.ts
index 8a85df0c..1e551d20 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1 +1 @@
-export const VERSION = '9.12.0'; // x-release-please-version
+export const VERSION = '9.12.1'; // x-release-please-version