diff --git a/.gitmodules b/.gitmodules
index dee05c7..70d07d3 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -19,3 +19,6 @@
 [submodule "lib/ring-buffer-lib"]
 	path = lib/ring-buffer-lib
 	url = https://github.com/GenerationSoftware/ring-buffer-lib
+[submodule "lib/uniform-random-number"]
+	path = lib/uniform-random-number
+	url = https://github.com/generationsoftware/uniform-random-number
diff --git a/lib/uniform-random-number b/lib/uniform-random-number
new file mode 160000
index 0000000..380d903
--- /dev/null
+++ b/lib/uniform-random-number
@@ -0,0 +1 @@
+Subproject commit 380d90359d6979bcd654bbc1bc8d77144afa3274
diff --git a/remappings.txt b/remappings.txt
index 3ef092d..dbeb410 100644
--- a/remappings.txt
+++ b/remappings.txt
@@ -4,3 +4,4 @@ openzeppelin=lib/openzeppelin-contracts/contracts/
 pt-v5-twab-controller/=lib/pt-v5-twab-controller/src/
 ring-buffer-lib/=lib/ring-buffer-lib/src/
 owner-manager-contracts/=lib/owner-manager-contracts/contracts/
+uniform-random-number/=lib/uniform-random-number/src/
\ No newline at end of file
diff --git a/src/libraries/TierCalculationLib.sol b/src/libraries/TierCalculationLib.sol
index cc4b68a..e8d060f 100644
--- a/src/libraries/TierCalculationLib.sol
+++ b/src/libraries/TierCalculationLib.sol
@@ -2,6 +2,7 @@
 
 pragma solidity ^0.8.19;
 
+import { UniformRandomNumber } from "uniform-random-number/UniformRandomNumber.sol";
 import { E, SD59x18, sd, unwrap, convert, ceil } from "prb-math/SD59x18.sol";
 import { UD60x18, convert as convertUD60x18 } from "prb-math/UD60x18.sol";
 
@@ -89,7 +90,7 @@ library TierCalculationLib {
                 - Portion of prize that was contributed by the vault
         */
     // first constrain the random number to be within the vault total supply
-    uint256 constrainedRandomNumber = _userSpecificRandomNumber % (_vaultTwabTotalSupply);
+    uint256 constrainedRandomNumber = UniformRandomNumber.uniform(_userSpecificRandomNumber, _vaultTwabTotalSupply);
     uint256 winningZone = calculateWinningZone(_userTwab, _vaultContributionFraction, _tierOdds);
 
     return constrainedRandomNumber < winningZone;