diff --git a/contracts/utils/contracts/src/LibAddressArray.sol b/contracts/utils/contracts/src/LibAddressArray.sol
index aa3ef27dfb..75ee5b2fb1 100644
--- a/contracts/utils/contracts/src/LibAddressArray.sol
+++ b/contracts/utils/contracts/src/LibAddressArray.sol
@@ -30,7 +30,8 @@ library LibAddressArray {
     /// @param addressToAppend  Address to append.
     /// @return Array of addresses: [... addressArray, addressToAppend]
     function append(address[] memory addressArray, address addressToAppend) 
-        internal pure
+        internal
+        pure
         returns (address[] memory)
     {
         // Get stats on address array and free memory
@@ -81,4 +82,18 @@ library LibAddressArray {
         addressArray[addressArrayLength - 1] = addressToAppend;
         return addressArray;
     }
+
+    function indexOf(address[] memory addressArray, address target)
+        internal
+        pure
+        returns (bool, uint256)
+    {
+        uint256 length = addressArray.length;
+        for (uint256 i = 0; i < length; i++) {
+            if (addressArray[i] == target) {
+                return (true, i);
+            }
+        }
+        return (false, 0);
+    }
 }