diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 729e38f6c..70c82990b 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -259,6 +259,16 @@ jobs:
             echo "No Solidity files to lint with Forge"
           fi
 
+      - name: Check OpenZeppelin v3 alias scope
+        run: |
+          # The @openzeppelin/contracts-v3 alias (SafeMath for 0.7.6 code) is only for graph-core
+          MATCHES=$(git grep -l '@openzeppelin/contracts-v3' -- '*.sol' ':!packages/graph-core/**') || [ $? -eq 1 ]
+          if [ -n "$MATCHES" ]; then
+            echo "@openzeppelin/contracts-v3 may only be imported from packages/graph-core:"
+            echo "$MATCHES"
+            exit 1
+          fi
+
       - name: Check lint results
         if: always()
         run: |
diff --git a/packages/contracts/contracts/epochs/EpochManager.sol b/packages/graph-core/contracts/epochs/EpochManager.sol
similarity index 94%
rename from packages/contracts/contracts/epochs/EpochManager.sol
rename to packages/graph-core/contracts/epochs/EpochManager.sol
index 2e3033d4f..771e67ae0 100644
--- a/packages/contracts/contracts/epochs/EpochManager.sol
+++ b/packages/graph-core/contracts/epochs/EpochManager.sol
@@ -5,10 +5,10 @@ pragma solidity ^0.7.6;
 // TODO: Re-enable and fix issues when publishing a new version
 // solhint-disable gas-indexed-events, gas-small-strings, gas-strict-inequalities
 
-import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
+import { SafeMath } from "@openzeppelin/contracts-v3/math/SafeMath.sol";
 
-import { GraphUpgradeable } from "@graphprotocol/graph-core/contracts/upgrades/GraphUpgradeable.sol";
-import { Managed } from "@graphprotocol/graph-core/contracts/governance/Managed.sol";
+import { GraphUpgradeable } from "../upgrades/GraphUpgradeable.sol";
+import { Managed } from "../governance/Managed.sol";
 
 import { EpochManagerV1Storage } from "./EpochManagerStorage.sol";
 import { IEpochManager } from "@graphprotocol/interfaces/contracts/contracts/epochs/IEpochManager.sol";
diff --git a/packages/contracts/contracts/epochs/EpochManagerStorage.sol b/packages/graph-core/contracts/epochs/EpochManagerStorage.sol
similarity index 87%
rename from packages/contracts/contracts/epochs/EpochManagerStorage.sol
rename to packages/graph-core/contracts/epochs/EpochManagerStorage.sol
index 3c3d8bdba..894f34a46 100644
--- a/packages/contracts/contracts/epochs/EpochManagerStorage.sol
+++ b/packages/graph-core/contracts/epochs/EpochManagerStorage.sol
@@ -2,7 +2,7 @@
 
 pragma solidity ^0.7.6;
 
-import { Managed } from "@graphprotocol/graph-core/contracts/governance/Managed.sol";
+import { Managed } from "../governance/Managed.sol";
 
 /**
  * @title Epoch Manager Storage V1
diff --git a/packages/graph-core/hardhat.config.ts b/packages/graph-core/hardhat.config.ts
index e974652ed..b0b396689 100644
--- a/packages/graph-core/hardhat.config.ts
+++ b/packages/graph-core/hardhat.config.ts
@@ -61,6 +61,9 @@ const config: HardhatUserConfig = {
     '@openzeppelin/contracts/**/*': {
       default: 'off',
     },
+    '@openzeppelin/contracts-v3/**/*': {
+      default: 'off',
+    },
   },
 }
 
diff --git a/packages/graph-core/package.json b/packages/graph-core/package.json
index 21955e65d..2adfb95d0 100644
--- a/packages/graph-core/package.json
+++ b/packages/graph-core/package.json
@@ -27,7 +27,8 @@
   },
   "dependencies": {
     "@graphprotocol/interfaces": "workspace:^",
-    "@openzeppelin/contracts": "^5.4.0"
+    "@openzeppelin/contracts": "^5.4.0",
+    "@openzeppelin/contracts-v3": "npm:@openzeppelin/contracts@3.4.2"
   },
   "devDependencies": {
     "@ethersproject/abi": "^5.8.0",
diff --git a/packages/horizon/test/unit/epochs/EpochManager.t.sol b/packages/graph-core/test/unit/epochs/EpochManager.t.sol
similarity index 91%
rename from packages/horizon/test/unit/epochs/EpochManager.t.sol
rename to packages/graph-core/test/unit/epochs/EpochManager.t.sol
index 6b21b8ef3..4afd9bdcb 100644
--- a/packages/horizon/test/unit/epochs/EpochManager.t.sol
+++ b/packages/graph-core/test/unit/epochs/EpochManager.t.sol
@@ -2,6 +2,7 @@
 pragma solidity ^0.8.27;
 
 import { IEpochManagerLike } from "./IEpochManagerLike.sol";
+import { VmSafe } from "forge-std/Vm.sol";
 import { ProtocolFixture } from "../shared/ProtocolFixture.t.sol";
 
 contract EpochManagerTest is ProtocolFixture {
@@ -17,7 +18,7 @@ contract EpochManagerTest is ProtocolFixture {
     function setUp() public {
         vm.warp(1_700_000_000);
         _deployProtocolBase();
-        address impl = _deployArtifact(string.concat(PKG_ARTIFACTS, "epochs/EpochManager.sol/EpochManager.json"), "");
+        address impl = _deployPkg("EpochManager.sol:EpochManager", "");
         epochManager = IEpochManagerLike(
             _deployBehindProxy(
                 impl,
@@ -26,6 +27,15 @@ contract EpochManagerTest is ProtocolFixture {
         );
     }
 
+    function test_Bytecode_FoundryMatchesHardhat() public {
+        vm.skip(vm.isContext(VmSafe.ForgeContext.Coverage));
+        string memory json = vm.readFile("artifacts/contracts/epochs/EpochManager.sol/EpochManager.json");
+        bytes memory hardhat = _stripMetadata(vm.parseJsonBytes(json, ".bytecode"));
+        bytes memory foundry = _stripMetadata(vm.getCode("EpochManager.sol:EpochManager"));
+        assertGt(hardhat.length, 0);
+        assertEq(foundry, hardhat);
+    }
+
     modifier withLifecycleLength() {
         vm.prank(governor);
         epochManager.setEpochLength(EPOCH_LENGTH);
diff --git a/packages/horizon/test/unit/epochs/IEpochManagerLike.sol b/packages/graph-core/test/unit/epochs/IEpochManagerLike.sol
similarity index 100%
rename from packages/horizon/test/unit/epochs/IEpochManagerLike.sol
rename to packages/graph-core/test/unit/epochs/IEpochManagerLike.sol
diff --git a/packages/graph-core/test/unit/shared/Fixture.t.sol b/packages/graph-core/test/unit/shared/Fixture.t.sol
index c3e3a0388..6286e2a7c 100644
--- a/packages/graph-core/test/unit/shared/Fixture.t.sol
+++ b/packages/graph-core/test/unit/shared/Fixture.t.sol
@@ -28,13 +28,6 @@ contract FixtureTest is GraphCoreTest {
         assertEq(foundry, hardhat);
     }
 
-    function _stripMetadata(bytes memory code) internal pure returns (bytes memory out) {
-        uint256 metadataLength = (uint256(uint8(code[code.length - 2])) << 8) | uint256(uint8(code[code.length - 1]));
-        uint256 newLength = code.length - metadataLength - 2;
-        out = new bytes(newLength);
-        for (uint256 i = 0; i < newLength; i++) out[i] = code[i];
-    }
-
     function test_Fixture_ProxyWiredToImplementation() public view {
         IGraphProxy proxy = IGraphProxy(address(managed));
         assertEq(proxyAdmin.getProxyAdmin(proxy), address(proxyAdmin));
diff --git a/packages/graph-core/test/unit/shared/ProtocolFixture.t.sol b/packages/graph-core/test/unit/shared/ProtocolFixture.t.sol
index f34f5e83e..e4863846f 100644
--- a/packages/graph-core/test/unit/shared/ProtocolFixture.t.sol
+++ b/packages/graph-core/test/unit/shared/ProtocolFixture.t.sol
@@ -44,4 +44,11 @@ abstract contract ProtocolFixture is Test {
         vm.prank(governor);
         controller.setContractProxy(keccak256(bytes(name)), addr);
     }
+
+    function _stripMetadata(bytes memory code) internal pure returns (bytes memory out) {
+        uint256 metadataLength = (uint256(uint8(code[code.length - 2])) << 8) | uint256(uint8(code[code.length - 1]));
+        uint256 newLength = code.length - metadataLength - 2;
+        out = new bytes(newLength);
+        for (uint256 i = 0; i < newLength; i++) out[i] = code[i];
+    }
 }
diff --git a/packages/horizon/foundry.toml b/packages/horizon/foundry.toml
index b3e1c7054..088193a98 100644
--- a/packages/horizon/foundry.toml
+++ b/packages/horizon/foundry.toml
@@ -5,7 +5,7 @@ libs = ["node_modules"]
 auto_detect_remappings = false
 test = 'test'
 cache_path = 'cache_forge'
-fs_permissions = [{ access = "read", path = "./" }, { access = "read", path = "node_modules/@graphprotocol/contracts/artifacts" }, { access = "read", path = "node_modules/@graphprotocol/graph-core/artifacts" }]
+fs_permissions = [{ access = "read", path = "./" }, { access = "read", path = "node_modules/@graphprotocol/graph-core/artifacts" }]
 solc_version = '0.8.35'
 evm_version = 'cancun'
 # Suppress solc warnings emitted from third-party code we don't control
diff --git a/packages/horizon/test/unit/shared/ProtocolFixture.t.sol b/packages/horizon/test/unit/shared/ProtocolFixture.t.sol
index e1567eaa9..561f83032 100644
--- a/packages/horizon/test/unit/shared/ProtocolFixture.t.sol
+++ b/packages/horizon/test/unit/shared/ProtocolFixture.t.sol
@@ -8,7 +8,6 @@ import { IGraphProxyAdmin } from "@graphprotocol/interfaces/contracts/contracts/
 
 abstract contract ProtocolFixture is Test {
     string internal constant CORE_ARTIFACTS = "node_modules/@graphprotocol/graph-core/artifacts/contracts/";
-    string internal constant PKG_ARTIFACTS = "node_modules/@graphprotocol/contracts/artifacts/contracts/";
 
     address internal governor; // makeAddr("governor"), set in _deployProtocolBase
     IController internal controller;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index b59b38c75..be105f5d8 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -583,6 +583,9 @@ importers:
       '@openzeppelin/contracts':
         specifier: ^5.4.0
         version: 5.4.0
+      '@openzeppelin/contracts-v3':
+        specifier: npm:@openzeppelin/contracts@3.4.2
+        version: '@openzeppelin/contracts@3.4.2'
     devDependencies:
       '@ethersproject/abi':
         specifier: ^5.8.0
diff --git a/scripts/contracts-migration/manifest.json b/scripts/contracts-migration/manifest.json
index 7b3059b47..5c5741093 100644
--- a/scripts/contracts-migration/manifest.json
+++ b/scripts/contracts-migration/manifest.json
@@ -12,7 +12,7 @@
   "GraphCurationToken": "packages/graph-token/artifacts/contracts/curation/GraphCurationToken.sol/GraphCurationToken.json",
   "SubgraphNFT": "packages/graph-token/artifacts/contracts/discovery/SubgraphNFT.sol/SubgraphNFT.json",
   "SubgraphNFTDescriptor": "packages/graph-token/artifacts/contracts/discovery/SubgraphNFTDescriptor.sol/SubgraphNFTDescriptor.json",
-  "EpochManager": "packages/contracts/artifacts/contracts/epochs/EpochManager.sol/EpochManager.json",
+  "EpochManager": "packages/graph-core/artifacts/contracts/epochs/EpochManager.sol/EpochManager.json",
   "RewardsManager": "packages/contracts/artifacts/contracts/rewards/RewardsManager.sol/RewardsManager.json",
   "HorizonStaking": "packages/horizon/build/contracts/contracts/staking/HorizonStaking.sol/HorizonStaking.json",
   "GraphPayments": "packages/horizon/build/contracts/contracts/payments/GraphPayments.sol/GraphPayments.json",