diff --git a/packages/hardhat-graph-protocol/src/sdk/deployments/horizon/address-book.ts b/packages/hardhat-graph-protocol/src/sdk/deployments/horizon/address-book.ts
index 4511757da..e940a6313 100644
--- a/packages/hardhat-graph-protocol/src/sdk/deployments/horizon/address-book.ts
+++ b/packages/hardhat-graph-protocol/src/sdk/deployments/horizon/address-book.ts
@@ -3,6 +3,9 @@ import { logDebug, logError } from '../../../logger'
 import { Provider, Signer } from 'ethers'
 import { AddressBook } from '../../address-book'
 import { assertObject } from '../../utils/assertion'
+import { Contract } from 'ethers'
+import { loadArtifact } from '../../lib/artifact'
+import { mergeABIs } from '../../utils/abi'
 
 import type { GraphHorizonContractName, GraphHorizonContracts } from './contracts'
 
@@ -23,6 +26,20 @@ export class GraphHorizonAddressBook extends AddressBook<number, GraphHorizonCon
       GraphHorizonArtifactsMap,
       signerOrProvider,
     )
+
+    // Handle HorizonStaking specially to include extension functions
+    if (contracts.HorizonStaking) {
+      const stakingOverride = new Contract(
+        this.getEntry('HorizonStaking').address,
+        mergeABIs(
+          loadArtifact('HorizonStaking', GraphHorizonArtifactsMap.HorizonStaking).abi,
+          loadArtifact('HorizonStakingExtension', GraphHorizonArtifactsMap.HorizonStaking).abi,
+        ),
+        signerOrProvider,
+      )
+      contracts.HorizonStaking = stakingOverride
+    }
+
     this._assertGraphHorizonContracts(contracts)
 
     // Aliases
diff --git a/packages/hardhat-graph-protocol/src/sdk/utils/abi.ts b/packages/hardhat-graph-protocol/src/sdk/utils/abi.ts
new file mode 100644
index 000000000..97b28973c
--- /dev/null
+++ b/packages/hardhat-graph-protocol/src/sdk/utils/abi.ts
@@ -0,0 +1,8 @@
+export function mergeABIs(abi1: any[], abi2: any[]) {
+  for (const item of abi2) {
+    if (abi1.find((v) => v.name === item.name) === undefined) {
+      abi1.push(item)
+    }
+  }
+  return abi1
+}
\ No newline at end of file