diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4aecdad..fe54049 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Kite v5 - TypeScript
 
+## [5.3.1] - 2026-04-24
+
+### Bug Fixes
+
+- **Type Definitions Sync**: Added missing `market_protection` parameter to `placeOrder` and `modifyOrder` method signatures in type definitions
+
 ## [5.3.0] - 2026-04-23
 
 ### New Features
diff --git a/package-lock.json b/package-lock.json
index 5d667bc..d4d27be 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "kiteconnect",
-  "version": "5.3.0",
+  "version": "5.3.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "kiteconnect",
-      "version": "5.3.0",
+      "version": "5.3.1",
       "license": "MIT",
       "dependencies": {
         "@microsoft/tsdoc": "^0.15.0",
diff --git a/package.json b/package.json
index 3840b92..1dac9bc 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "kiteconnect",
-  "version": "5.3.0",
+  "version": "5.3.1",
   "description": "The official typescript client for the Kite Connect trading APIs",
   "main": "./dist/lib/index.js",
   "types": "./types/index.d.ts",
diff --git a/types/connect.d.ts b/types/connect.d.ts
index 270a482..6efd714 100644
--- a/types/connect.d.ts
+++ b/types/connect.d.ts
@@ -1263,7 +1263,6 @@ export type VirtualContractResponse = {
       total: number;
    };
 }
-
 export type GTTParams = {
   /**
    * GTT type, its either self.GTT_TYPE_OCO or self.GTT_TYPE_SINGLE.
@@ -2030,6 +2029,10 @@ export type Connect = {
        * Parent order id incase of multilegged orders.
        */
       parent_order_id?: string;
+      /**
+       * Market protection percentage. Set to -1 for system default, or 0-100.
+       */
+      market_protection?: number;
     }
   ) => Promise<{ order_id: string }>;
 
@@ -2218,6 +2221,10 @@ export type Connect = {
        * When true, the response's `children` array contains per-slice results.
        */
       autoslice?: boolean;
+      /**
+        * Market protection percentage. Set to -1 for system default, or 0-100.
+      */
+      market_protection?: number;
     }
   ) => Promise<AutosliceOrderResponse>;