diff --git a/packages/horizon/contracts/interfaces/internal/IHorizonStakingMain.sol b/packages/horizon/contracts/interfaces/internal/IHorizonStakingMain.sol
index 25c5f85aa..e296f88e5 100644
--- a/packages/horizon/contracts/interfaces/internal/IHorizonStakingMain.sol
+++ b/packages/horizon/contracts/interfaces/internal/IHorizonStakingMain.sol
@@ -352,6 +352,11 @@ interface IHorizonStakingMain {
      */
     error HorizonStakingInvalidThawingPeriod(uint64 thawingPeriod, uint64 maxThawingPeriod);
 
+    /**
+     * @notice Thrown when attempting to create a provision for a data service that already has a provision.
+     */
+    error HorizonStakingProvisionAlreadyExists();
+
     // -- Errors: stake --
 
     /**
diff --git a/packages/horizon/contracts/staking/HorizonStaking.sol b/packages/horizon/contracts/staking/HorizonStaking.sol
index 4d3349b7a..45ce7c8cb 100644
--- a/packages/horizon/contracts/staking/HorizonStaking.sol
+++ b/packages/horizon/contracts/staking/HorizonStaking.sol
@@ -606,6 +606,7 @@ contract HorizonStaking is HorizonStakingBase, IHorizonStakingMain {
             _thawingPeriod <= _maxThawingPeriod,
             HorizonStakingInvalidThawingPeriod(_thawingPeriod, _maxThawingPeriod)
         );
+        require(_provisions[_serviceProvider][_verifier].createdAt == 0, HorizonStakingProvisionAlreadyExists());
         uint256 tokensIdle = _getIdleStake(_serviceProvider);
         require(_tokens <= tokensIdle, HorizonStakingInsufficientIdleStake(_tokens, tokensIdle));
 
diff --git a/packages/horizon/test/staking/provision/provision.t.sol b/packages/horizon/test/staking/provision/provision.t.sol
index fc941ec7f..3394460fb 100644
--- a/packages/horizon/test/staking/provision/provision.t.sol
+++ b/packages/horizon/test/staking/provision/provision.t.sol
@@ -6,7 +6,6 @@ import "forge-std/Test.sol";
 import { HorizonStakingTest } from "../HorizonStaking.t.sol";
 
 contract HorizonStakingProvisionTest is HorizonStakingTest {
-
     /*
      * TESTS
      */
@@ -68,6 +67,21 @@ contract HorizonStakingProvisionTest is HorizonStakingTest {
         staking.provision(users.indexer, subgraphDataServiceAddress, provisionTokens, 0, 0);
     }
 
+    function testProvision_RevertWhen_AlreadyExists(
+        uint256 amount,
+        uint32 maxVerifierCut,
+        uint64 thawingPeriod
+    ) public useIndexer useProvision(amount / 2, maxVerifierCut, thawingPeriod) {
+        resetPrank(users.indexer);
+
+        token.approve(address(staking), amount / 2);
+        staking.stake(amount / 2);
+
+        bytes memory expectedError = abi.encodeWithSignature("HorizonStakingProvisionAlreadyExists()");
+        vm.expectRevert(expectedError);
+        staking.provision(users.indexer, subgraphDataServiceAddress, amount / 2, maxVerifierCut, thawingPeriod);
+    }
+
     function testProvision_OperatorAddTokensToProvision(
         uint256 amount,
         uint32 maxVerifierCut,
@@ -94,7 +108,7 @@ contract HorizonStakingProvisionTest is HorizonStakingTest {
     ) public useIndexer useProvision(amount, maxVerifierCut, thawingPeriod) {
         vm.startPrank(users.operator);
         bytes memory expectedError = abi.encodeWithSignature(
-            "HorizonStakingNotAuthorized(address,address,address)", 
+            "HorizonStakingNotAuthorized(address,address,address)",
             users.operator,
             users.indexer,
             subgraphDataServiceAddress
@@ -102,4 +116,4 @@ contract HorizonStakingProvisionTest is HorizonStakingTest {
         vm.expectRevert(expectedError);
         staking.provision(users.indexer, subgraphDataServiceAddress, amount, maxVerifierCut, thawingPeriod);
     }
-}
\ No newline at end of file
+}