diff --git a/contracts/modules/STO/USDTiered/USDTieredSTO.sol b/contracts/modules/STO/USDTiered/USDTieredSTO.sol
index 67b2fc6f1..c042ee127 100644
--- a/contracts/modules/STO/USDTiered/USDTieredSTO.sol
+++ b/contracts/modules/STO/USDTiered/USDTieredSTO.sol
@@ -190,6 +190,23 @@ contract USDTieredSTO is USDTieredSTOStorage, STO {
         _modifyAddresses(_wallet, _treasuryWallet, _usdTokens);
     }
 
+    /**
+     * @dev Modifies Oracle address.
+     *      By default, Polymath oracles are used but issuer can overide them using this function
+     *      Set _oracleAddress to 0x0 to fallback to using Polymath oracles
+     * @param _fundRaiseType Actual currency
+     * @param _oracleAddress address of the oracle
+     */
+    function modifyOracle(FundRaiseType _fundRaiseType, address _oracleAddress) external {
+        _onlySecurityTokenOwner();
+        if (_fundRaiseType == FundRaiseType.ETH) {
+            customOracles[bytes32("ETH")][bytes32("USD")] = _oracleAddress;
+        } else {
+            require(_fundRaiseType == FundRaiseType.POLY, "Invalid currency");
+            customOracles[bytes32("POLY")][bytes32("USD")] = _oracleAddress;
+        }
+    }
+
     function _modifyLimits(uint256 _nonAccreditedLimitUSD, uint256 _minimumInvestmentUSD) internal {
         minimumInvestmentUSD = _minimumInvestmentUSD;
         nonAccreditedLimitUSD = _nonAccreditedLimitUSD;
@@ -757,8 +774,9 @@ contract USDTieredSTO is USDTieredSTOStorage, STO {
         return this.configure.selector;
     }
 
-    function _getOracle(bytes32 _currency, bytes32 _denominatedCurrency) internal view returns(address) {
-        return IPolymathRegistry(ISecurityToken(securityToken).polymathRegistry()).getAddress(oracleKeys[_currency][_denominatedCurrency]);
+    function _getOracle(bytes32 _currency, bytes32 _denominatedCurrency) internal view returns(address oracleAddress) {
+        oracleAddress = customOracles[_currency][_denominatedCurrency];
+        if (oracleAddress == address(0))
+            oracleAddress =  IPolymathRegistry(ISecurityToken(securityToken).polymathRegistry()).getAddress(oracleKeys[_currency][_denominatedCurrency]);
     }
-
 }
diff --git a/contracts/modules/STO/USDTiered/USDTieredSTOStorage.sol b/contracts/modules/STO/USDTiered/USDTieredSTOStorage.sol
index 75a1f6d1c..15cc553ae 100644
--- a/contracts/modules/STO/USDTiered/USDTieredSTOStorage.sol
+++ b/contracts/modules/STO/USDTiered/USDTieredSTOStorage.sol
@@ -74,4 +74,6 @@ contract USDTieredSTOStorage {
     // Array of Tiers
     Tier[] public tiers;
 
+    // Optional custom Oracles.
+    mapping(bytes32 => mapping(bytes32 => address)) customOracles;
 }
diff --git a/test/p_usd_tiered_sto.js b/test/p_usd_tiered_sto.js
index 9148dfe7a..f7b014180 100644
--- a/test/p_usd_tiered_sto.js
+++ b/test/p_usd_tiered_sto.js
@@ -35,6 +35,8 @@ contract("USDTieredSTO", async (accounts) => {
     let ETH = 0;
     let POLY = 1;
     let DAI = 2;
+    let oldEthRate;
+    let oldPolyRate;
 
     let MESSAGE = "Transaction Should Fail!";
     const GAS_PRICE = 0;
@@ -909,6 +911,40 @@ contract("USDTieredSTO", async (accounts) => {
     });
 
     describe("Test modifying configuration", async () => {
+        it("Should not allow unauthorized address to change oracle address", async () => {
+            let stoId = 3;
+            await catchRevert(I_USDTieredSTO_Array[stoId].modifyOracle(ETH, address_zero, { from: ACCREDITED1 }));
+        });
+
+        it("Should not allow to change oracle address for currencies other than ETH and POLY", async () => {
+            let stoId = 3;
+            await catchRevert(I_USDTieredSTO_Array[stoId].modifyOracle(DAI, address_zero, { from: ISSUER }));
+        });
+
+        it("Should allow to change oracle address for ETH", async () => {
+            let stoId = 3;
+            oldEthRate = await I_USDTieredSTO_Array[stoId].getRate.call(ETH);
+            let I_USDOracle2 = await MockOracle.new(address_zero, web3.utils.fromAscii("ETH"), web3.utils.fromAscii("USD"), e18, { from: POLYMATH });
+            await I_USDTieredSTO_Array[stoId].modifyOracle(ETH, I_USDOracle2.address, { from: ISSUER });
+            assert.equal((await I_USDTieredSTO_Array[stoId].getRate.call(ETH)).toString(), e18.toString());
+        });
+
+        it("Should allow to change oracle address for POLY", async () => {
+            let stoId = 3;
+            oldPolyRate = await I_USDTieredSTO_Array[stoId].getRate.call(POLY);
+            let I_POLYOracle2 = await MockOracle.new(I_PolyToken.address, web3.utils.fromAscii("POLY"), web3.utils.fromAscii("USD"), e18, { from: POLYMATH });
+            await I_USDTieredSTO_Array[stoId].modifyOracle(POLY, I_POLYOracle2.address, { from: ISSUER });
+            assert.equal((await I_USDTieredSTO_Array[stoId].getRate.call(POLY)).toString(), e18.toString());
+        });
+
+        it("Should use official oracles when custom oracle is set to 0x0", async () => {
+            let stoId = 3;
+            await I_USDTieredSTO_Array[stoId].modifyOracle(ETH, address_zero, { from: ISSUER });
+            await I_USDTieredSTO_Array[stoId].modifyOracle(POLY, address_zero, { from: ISSUER });
+            assert.equal((await I_USDTieredSTO_Array[stoId].getRate.call(ETH)).toString(), oldEthRate.toString());
+            assert.equal((await I_USDTieredSTO_Array[stoId].getRate.call(POLY)).toString(), oldPolyRate.toString());
+        });
+
         it("Should successfully change config before startTime - funding", async () => {
             let stoId = 3;
             await I_USDTieredSTO_Array[stoId].modifyFunding([0], { from: ISSUER });