diff --git a/src/lib/config/contracts.ts b/src/lib/config/contracts.ts
index dee5669..513aad4 100644
--- a/src/lib/config/contracts.ts
+++ b/src/lib/config/contracts.ts
@@ -17,6 +17,12 @@ export const MAINNET_CONTRACTS = {
 
   // Stacking
   POX_4: "SP000000000000000000002Q6VF78.pox-4",
+  // Epoch 4.0 hard fork (stacks-core 4.0.1): pox-5 replaces pox-4 at the same
+  // boot-contract address, following the pox-2/pox-3/pox-4 deployment pattern.
+  // Prefer resolving the active PoX contract dynamically via
+  // StackingService.getActivePoxContract() (reads /v2/pox contract_id);
+  // this is the static fallback if that lookup fails.
+  POX_5: "SP000000000000000000002Q6VF78.pox-5",
 
   // ALEX DEX (SDK handles most operations, but we need pool contract for queries)
   ALEX_AMM_POOL: "SP3K8BC0PPEVCV7NZ6QSRWPQ2JE9E5B6N3PA0KBR9.amm-swap-pool-v1-1",
@@ -167,6 +173,7 @@ export const TESTNET_CONTRACTS = {
 
   // Stacking
   POX_4: "ST000000000000000000002AMW42H.pox-4",
+  POX_5: "ST000000000000000000002AMW42H.pox-5",
 
   // ERC-8004 Identity & Reputation
   IDENTITY_REGISTRY: "ST3YT0XW92E6T2FE59B2G5N2WNNFSBZ6MZKQS5D18.identity-registry-v2",
diff --git a/src/lib/services/stacking.service.ts b/src/lib/services/stacking.service.ts
index beadf8b..0aaefc6 100644
--- a/src/lib/services/stacking.service.ts
+++ b/src/lib/services/stacking.service.ts
@@ -38,6 +38,24 @@ export class StackingService {
     return this.hiro.getPoxInfo();
   }
 
+  /**
+   * Resolve the currently active PoX contract (e.g. pox-4, pox-5) from the
+   * node's /v2/pox response, instead of hardcoding a version. Falls back to
+   * the static POX_5 contract if the lookup fails, so stacking keeps working
+   * across future PoX version bumps without a code change.
+   */
+  private async getActivePoxContract(): Promise<string> {
+    try {
+      const poxInfo = await this.hiro.getPoxInfo();
+      if (poxInfo?.contract_id) {
+        return poxInfo.contract_id;
+      }
+    } catch {
+      // Fall through to static fallback
+    }
+    return this.contracts.POX_5;
+  }
+
   /**
    * Get stacking status for an address
    * Note: Returns whether the address is stacking, but detailed amounts require proper CV parsing
@@ -45,7 +63,7 @@ export class StackingService {
   async getStackingStatus(address: string): Promise<StackingStatus> {
     try {
       const result = await this.hiro.callReadOnlyFunction(
-        this.contracts.POX_4,
+        await this.getActivePoxContract(),
         "get-stacker-info",
         [{ type: "principal", value: address } as unknown as ClarityValue],
         address
@@ -87,7 +105,9 @@ export class StackingService {
     startBurnHeight: number,
     lockPeriod: number
   ): Promise<TransferResult> {
-    const { address: contractAddress, name: contractName } = parseContractId(this.contracts.POX_4);
+    const { address: contractAddress, name: contractName } = parseContractId(
+      await this.getActivePoxContract()
+    );
 
     const functionArgs: ClarityValue[] = [
       uintCV(amount),
@@ -123,7 +143,9 @@ export class StackingService {
     extendCount: number,
     poxAddress: { version: number; hashbytes: string }
   ): Promise<TransferResult> {
-    const { address: contractAddress, name: contractName } = parseContractId(this.contracts.POX_4);
+    const { address: contractAddress, name: contractName } = parseContractId(
+      await this.getActivePoxContract()
+    );
 
     const functionArgs: ClarityValue[] = [
       uintCV(extendCount),
@@ -150,7 +172,9 @@ export class StackingService {
     account: Account,
     increaseAmount: bigint
   ): Promise<TransferResult> {
-    const { address: contractAddress, name: contractName } = parseContractId(this.contracts.POX_4);
+    const { address: contractAddress, name: contractName } = parseContractId(
+      await this.getActivePoxContract()
+    );
 
     const functionArgs: ClarityValue[] = [uintCV(increaseAmount)];
 
@@ -180,7 +204,9 @@ export class StackingService {
     untilBurnHeight?: number,
     poxAddress?: { version: number; hashbytes: string }
   ): Promise<TransferResult> {
-    const { address: contractAddress, name: contractName } = parseContractId(this.contracts.POX_4);
+    const { address: contractAddress, name: contractName } = parseContractId(
+      await this.getActivePoxContract()
+    );
 
     const functionArgs: ClarityValue[] = [
       uintCV(amount),
@@ -208,7 +234,9 @@ export class StackingService {
    * Revoke delegation
    */
   async revokeDelegation(account: Account): Promise<TransferResult> {
-    const { address: contractAddress, name: contractName } = parseContractId(this.contracts.POX_4);
+    const { address: contractAddress, name: contractName } = parseContractId(
+      await this.getActivePoxContract()
+    );
 
     // No assets moved from sender (revokes delegation permission)
     return callContract(account, {