diff --git a/.gas-snapshot b/.gas-snapshot
index 96ca0c509..5ea3520a5 100644
--- a/.gas-snapshot
+++ b/.gas-snapshot
@@ -128,9 +128,9 @@ EscrowedEXATest:testWithdrawFromUnknownStream() (gas: 899015)
 EscrowedEXATest:testWithdrawMaxFromMultipleStreams() (gas: 1014578)
 EscrowedEXATest:testWithdrawMaxShouldGiveReserveBackWhenDepleted() (gas: 329285)
 EscrowedEXATest:testWithdrawMaxWithInvalidSender() (gas: 342488)
-InterestRateModelTest:testFixedBorrowRate() (gas: 17380)
-InterestRateModelTest:testFloatingBorrowRate() (gas: 10725)
-InterestRateModelTest:testRevertMaxUtilizationLowerThanWad() (gas: 38822)
+InterestRateModelTest:testFixedBorrowRate() (gas: 1622881)
+InterestRateModelTest:testFloatingBorrowRate() (gas: 1616225)
+InterestRateModelTest:testRevertMaxUtilizationLowerThanWad() (gas: 60820)
 MarketTest:testAccountLiquidityAdjustedDebt() (gas: 383489)
 MarketTest:testAnotherUserRedeemWhenOwnerHasShortfall() (gas: 488711)
 MarketTest:testAnotherUserWithdrawWhenOwnerHasShortfall() (gas: 476505)
@@ -162,7 +162,7 @@ MarketTest:testDepositShouldUpdateFlexibleBorrowVariables() (gas: 447456)
 MarketTest:testDepositToSmartPool() (gas: 160015)
 MarketTest:testDistributeMultipleAccumulatedEarnings() (gas: 591785)
 MarketTest:testDistributionOfLossesShouldReduceFromFloatingBackupBorrowedAccordingly() (gas: 2064134)
-MarketTest:testEarlyRepaymentWithExcessiveAmountOfFees() (gas: 2414528)
+MarketTest:testEarlyRepaymentWithExcessiveAmountOfFees() (gas: 2436532)
 MarketTest:testEarlyWithdrawFromFreeLunchShouldNotRevertWithFloatingFullUtilization() (gas: 616605)
 MarketTest:testFixedBorrowFailingWhenFlexibleBorrowAccruesDebt() (gas: 790083)
 MarketTest:testFlexibleBorrow() (gas: 331283)
@@ -211,8 +211,8 @@ MarketTest:testRoundingUpAllowanceWhenBorrowingAtMaturity() (gas: 502600)
 MarketTest:testRoundingUpAllowanceWhenWithdrawingAtMaturity() (gas: 526520)
 MarketTest:testSetDampSpeedFactorShouldUpdateFloatingAssetsAverage() (gas: 243646)
 MarketTest:testSetEarningsAccumulatorSmoothFactorShouldDistributeEarnings() (gas: 498256)
-MarketTest:testSetInterestRateModelShouldUpdateFloatingDebt() (gas: 2071495)
-MarketTest:testSetInterestRateModelWithAddressZeroShouldNotUpdateFloatingDebt() (gas: 1934185)
+MarketTest:testSetInterestRateModelShouldUpdateFloatingDebt() (gas: 2093500)
+MarketTest:testSetInterestRateModelWithAddressZeroShouldNotUpdateFloatingDebt() (gas: 1956190)
 MarketTest:testShareValueNotDecreasingAfterDeposit() (gas: 473662)
 MarketTest:testShareValueNotDecreasingWhenMintingToTreasury() (gas: 479429)
 MarketTest:testSingleFloatingBorrow() (gas: 328409)
@@ -247,24 +247,24 @@ PreviewerTest:testAccountsReturningUtilizationForDifferentMaturities() (gas: 344
 PreviewerTest:testAccountsWithAccountOnlyDeposit() (gas: 808724)
 PreviewerTest:testAccountsWithAccountThatHasBalances() (gas: 1701237)
 PreviewerTest:testAccountsWithEmptyAccount() (gas: 657917)
-PreviewerTest:testAccountsWithIntermediateOperationsReturningAccurateAmounts() (gas: 15073942)
+PreviewerTest:testAccountsWithIntermediateOperationsReturningAccurateAmounts() (gas: 15095805)
 PreviewerTest:testActualTimeBeforeStartDistributionRewards() (gas: 6961056)
 PreviewerTest:testEmptyExactly() (gas: 5154447)
 PreviewerTest:testExactlyReturningInterestRateModelData() (gas: 652454)
-PreviewerTest:testFixedAvailableLiquidityProjectingNewFloatingDebt() (gas: 11146231)
-PreviewerTest:testFixedPoolsA() (gas: 16307078)
+PreviewerTest:testFixedAvailableLiquidityProjectingNewFloatingDebt() (gas: 11168094)
+PreviewerTest:testFixedPoolsA() (gas: 16328941)
 PreviewerTest:testFixedPoolsChangingMaturityInTime() (gas: 1594625)
-PreviewerTest:testFixedPoolsRatesAndUtilizations() (gas: 12649750)
-PreviewerTest:testFixedPoolsWithFloatingAssetsAverage() (gas: 13419439)
-PreviewerTest:testFlexibleAvailableLiquidity() (gas: 14713502)
+PreviewerTest:testFixedPoolsRatesAndUtilizations() (gas: 12671613)
+PreviewerTest:testFixedPoolsWithFloatingAssetsAverage() (gas: 13441302)
+PreviewerTest:testFlexibleAvailableLiquidity() (gas: 14735365)
 PreviewerTest:testFlexibleBorrowSharesAndAssets() (gas: 3662843)
-PreviewerTest:testFloatingAvailableLiquidityProjectingNewFloatingDebt() (gas: 10729434)
+PreviewerTest:testFloatingAvailableLiquidityProjectingNewFloatingDebt() (gas: 10751297)
 PreviewerTest:testFloatingRateAndUtilization() (gas: 977666)
 PreviewerTest:testJustUpdatedRewardRatesShouldStillReturnRate() (gas: 6227146)
 PreviewerTest:testMaxBorrowAssetsCapacity() (gas: 2110157)
-PreviewerTest:testMaxBorrowAssetsCapacityForAccountWithShortfall() (gas: 9434504)
-PreviewerTest:testMaxBorrowAssetsCapacityPerMarket() (gas: 10922291)
-PreviewerTest:testOraclePriceReturningAccurateValues() (gas: 8959402)
+PreviewerTest:testMaxBorrowAssetsCapacityForAccountWithShortfall() (gas: 9456367)
+PreviewerTest:testMaxBorrowAssetsCapacityPerMarket() (gas: 10944154)
+PreviewerTest:testOraclePriceReturningAccurateValues() (gas: 8981265)
 PreviewerTest:testPreviewBorrowAtAllMaturitiesReturningAccurateAmount() (gas: 3106487)
 PreviewerTest:testPreviewBorrowAtMaturityReturningAccurateAmount() (gas: 524407)
 PreviewerTest:testPreviewBorrowAtMaturityReturningAccurateAmountWithIntermediateOperations() (gas: 1189931)
@@ -308,8 +308,8 @@ PreviewerTest:testPreviewWithdrawAtMaturityWithZeroAmount() (gas: 220408)
 PreviewerTest:testReturnRewardAssetUsdPrice() (gas: 6181312)
 PreviewerTest:testRewardsRateAfterDistributionEnd() (gas: 6389417)
 PreviewerTest:testRewardsRateOnlyWithFixedBorrows() (gas: 6142939)
-PreviewerTest:testRewardsRateWithDifferentRewardLengths() (gas: 16918109)
-PreviewerTest:testRewardsRateWithMarketWithDifferentDecimals() (gas: 16165445)
+PreviewerTest:testRewardsRateWithDifferentRewardLengths() (gas: 16939972)
+PreviewerTest:testRewardsRateWithMarketWithDifferentDecimals() (gas: 16187308)
 PreviewerTest:testRewardsRateX() (gas: 7187998)
 PriceFeedDoubleTest:testPriceFeedDoubleReturningAccurateDecimals() (gas: 433304)
 PriceFeedDoubleTest:testPriceFeedDoubleReturningPrice() (gas: 26165)
diff --git a/scripts/irm-fixed.sh b/scripts/irm-fixed.sh
index b11ba72a8..539dee08a 100755
--- a/scripts/irm-fixed.sh
+++ b/scripts/irm-fixed.sh
@@ -1,25 +1,26 @@
 #!/usr/bin/env bash
 
-read -ra input <<< "$(cast abi-decode "_()(uint256,uint256,uint256,int256,int256,uint256,uint256,uint256,uint256,uint256)" "$1" | sed 's/ .*//' | xargs)"
+read -ra input <<< "$(cast abi-decode "_()(uint256,uint256,int256,int256,int256,uint256,uint256,uint256,uint256,uint256)" "$1" | sed 's/ .*//' | xargs)"
 
 rate=$(bc -l <<< "
   scale     = 2 * 18
 
   wad       = 1000000000000000000
-  ufixed    = ${input[0]} / wad
-  uglobal   = ${input[1]} / wad
-  fixedunat = ${input[2]} / wad
-  base      = ${input[3]} / wad
+  base      = ${input[0]} / wad
+  fixedunat = ${input[1]} / wad
+  spreadf   = ${input[2]} / wad
+  tpref     = ${input[3]} / wad
   ttmspeed  = ${input[4]} / wad
-  spreadf   = ${input[5]} / wad
-  tpref     = ${input[6]} / wad
-  maxpools  = ${input[7]}
-  maturity  = ${input[8]}
+  maturity  = ${input[5]}
+  maxpools  = ${input[6]}
+  ufixed    = ${input[7]} / wad
+  uglobal   = ${input[8]} / wad
   timestamp = ${input[9]}
 
   if (ufixed == 0) {
     rate      = base
-  } else { sqalpha   = maxpools / fixedunat
+  } else {
+    sqalpha   = maxpools / fixedunat
     alpha     = sqrt(sqalpha)
     sqx       = maxpools * ufixed / (uglobal * fixedunat)
     x         = sqrt(sqx)
diff --git a/scripts/irm-floating.sh b/scripts/irm-floating.sh
index 663d8a8fe..4b3df4fd1 100755
--- a/scripts/irm-floating.sh
+++ b/scripts/irm-floating.sh
@@ -1,19 +1,19 @@
 #!/usr/bin/env bash
 
-read -ra input <<< "$(cast abi-decode "_()(uint256,uint256,uint256,int256,uint256,uint256,uint256,uint256)" "$1" | sed 's/ .*//' | xargs)"
+read -ra input <<< "$(cast abi-decode "_()(uint256,int256,uint256,uint256,int256,int256,uint256,uint256)" "$1" | sed 's/ .*//' | xargs)"
 
 rate=$(bc -l <<< "
   scale     = 2 * 18
 
   wad       = 1000000000000000000
-  ufloating = ${input[0]} / wad
-  uglobal   = ${input[1]} / wad
-  unat      = ${input[2]} / wad
-  a         = ${input[3]} / wad
-  b         = ${input[4]} / wad
-  umax      = ${input[5]} / wad
-  sspeed    = ${input[6]} / wad
-  gspeed    = ${input[7]} / wad
+  a         = ${input[0]} / wad
+  b         = ${input[1]} / wad
+  umax      = ${input[2]} / wad
+  unat      = ${input[3]} / wad
+  sspeed    = ${input[4]} / wad
+  gspeed    = ${input[5]} / wad
+  ufloating = ${input[6]} / wad
+  uglobal   = ${input[7]} / wad
   
   r = a / (umax - ufloating) + b
 
diff --git a/test/InterestRateModel.t.sol b/test/InterestRateModel.t.sol
index 748f49b47..f2987a71a 100644
--- a/test/InterestRateModel.t.sol
+++ b/test/InterestRateModel.t.sol
@@ -1,44 +1,25 @@
 // SPDX-License-Identifier: BUSL-1.1
 pragma solidity ^0.8.17;
 
+import { Test } from "forge-std/Test.sol";
 import { MockERC20 } from "solmate/src/test/utils/mocks/MockERC20.sol";
 import { ERC1967Proxy } from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
-import { Test, stdError } from "forge-std/Test.sol";
 import { FixedPointMathLib } from "solmate/src/utils/FixedPointMathLib.sol";
-import { Market, InterestRateModel, UtilizationExceeded } from "../contracts/InterestRateModel.sol";
+import { Market, InterestRateModel } from "../contracts/InterestRateModel.sol";
 import { FixedLib } from "../contracts/utils/FixedLib.sol";
 import { Auditor } from "../contracts/Auditor.sol";
 
 contract InterestRateModelTest is Test {
   using FixedPointMathLib for uint256;
-  using FixedPointMathLib for uint32;
 
   InterestRateModelHarness internal irm;
 
-  function setUp() external {
-    irm = new InterestRateModelHarness(
-      Market(address(0)),
-      1.3829e16,
-      1.7429e16,
-      1.1e18,
-      7e17,
-      2.5e18,
-      1e18,
-      15_000e16,
-      0.2e18,
-      0,
-      0.5e18
-    );
-  }
-
   function testFixedBorrowRate() external {
-    uint256 rate = irm.fixedRate(FixedLib.INTERVAL, 6, 0.5e18, 0, 0.5e18);
-    assertEq(rate, 34290689491520350);
+    assertEq(deployDefault().fixedRate(FixedLib.INTERVAL, 6, 0.75e18, 0, 0.75e18), 63725347776211630);
   }
 
   function testFloatingBorrowRate() external {
-    uint256 rate = irm.floatingRate(0.5e18, 0.5e18);
-    assertEq(rate, 42772870834956443);
+    assertEq(deployDefault().floatingRate(0.75e18, 0.75e18), 79997731751740314);
   }
 
   function testRevertMaxUtilizationLowerThanWad() external {
@@ -58,110 +39,152 @@ contract InterestRateModelTest is Test {
     );
   }
 
-  function testFuzzReferenceFloatingRate(uint64 uFloating, uint64 uGlobal) external {
-    uFloating = uint64(_bound(uFloating, 0, 1e18));
-    uGlobal = uint64(_bound(uGlobal, 0, 1e18));
+  function testFuzzReferenceRateFloating(uint256 uFloating, uint256 uGlobal, FloatingParameters memory p) external {
+    uFloating = _bound(uFloating, 0, 1.01e18);
+    uGlobal = _bound(uGlobal, uFloating, 1.01e18);
+    p.naturalUtilization = _bound(p.naturalUtilization, 0.1e18, 0.9e18);
+    p.maxUtilization = _bound(p.maxUtilization, 1e18 + 1, 2e18);
+    p.growthSpeed = _bound(p.growthSpeed, 1, 5e18);
+    (p.curveA, p.curveB) = boundCurve(
+      p.curveA,
+      uint256(p.curveB),
+      p.naturalUtilization,
+      p.maxUtilization,
+      p.growthSpeed
+    );
+    p.sigmoidSpeed = _bound(p.sigmoidSpeed, 1, 10e18);
+    p.maxRate = _bound(p.maxRate, 1, 15_000e16);
+
+    irm = new InterestRateModelHarness(
+      Market(address(0)),
+      p.curveA,
+      p.curveB,
+      p.maxUtilization,
+      p.naturalUtilization,
+      p.sigmoidSpeed,
+      p.growthSpeed,
+      p.maxRate,
+      1,
+      0,
+      1
+    );
 
     uint256 refRate;
-    if (uFloating > uGlobal) {
-      vm.expectRevert(UtilizationExceeded.selector);
-    } else if (uGlobal >= 1e18) {
-      refRate = irm.maxRate();
+    if (uGlobal >= 1e18) {
+      refRate = p.maxRate;
     } else {
       string[] memory ffi = new string[](2);
       ffi[0] = "scripts/irm-floating.sh";
       ffi[1] = encodeHex(
         abi.encode(
+          p.curveA,
+          p.curveB,
+          p.maxUtilization,
+          p.naturalUtilization,
+          p.sigmoidSpeed,
+          p.growthSpeed,
           uFloating,
-          uGlobal,
-          irm.floatingNaturalUtilization(),
-          irm.floatingCurveA(),
-          irm.floatingCurveB(),
-          irm.floatingMaxUtilization(),
-          irm.sigmoidSpeed(),
-          irm.growthSpeed()
+          uGlobal
         )
       );
       refRate = abi.decode(vm.ffi(ffi), (uint256));
-      if (refRate > irm.maxRate()) refRate = irm.maxRate();
+      if (refRate > p.maxRate) refRate = p.maxRate;
     }
     uint256 rate = irm.floatingRate(uFloating, uGlobal);
 
-    assertApproxEqRel(rate, refRate, 1e4, "rate != expected");
-    assertLe(rate, irm.maxRate(), "rate > maxRate");
+    assertLe(rate, p.maxRate, "rate > maxRate");
+    assertApproxEqRel(rate, refRate, 1e12, "rate != refRate");
   }
 
-  function testFuzzReferenceFixedRate(
-    uint32 maturity,
-    uint8 maxPools,
-    uint64 uFixed,
-    uint64 uFloating,
-    uint64 uGlobal
+  function testFuzzReferenceRateFixed(
+    uint256 maturity,
+    uint256 maxPools,
+    uint256 uFixed,
+    uint256 uFloating,
+    uint256 uGlobal,
+    FixedParameters memory p
   ) external {
-    maxPools = uint8(_bound(maxPools, 1, 24));
-    maturity = uint32(_bound(maturity, 1, maxPools) * FixedLib.INTERVAL);
-    uFixed = uint64(_bound(uFixed, 0, 1.01e18));
-    uFloating = uint64(_bound(uFloating, 0, 1.01e18 - uFixed));
-    uGlobal = uint64(_bound(uGlobal, uFixed + uFloating, 1.01e18));
+    maxPools = _bound(maxPools, 6, 24); // deviation sensitivity < 5
+    maturity = _bound(maturity, 1, maxPools) * FixedLib.INTERVAL;
+    uFixed = _bound(uFixed, 0, 1.01e18);
+    uFloating = _bound(uFloating, 0, 1.01e18 - uFixed);
+    uGlobal = _bound(uGlobal, uFixed + uFloating, 1.01e18);
+    p.naturalUtilization = _bound(p.naturalUtilization, 0.1e18, 0.9e18);
+    p.maxUtilization = _bound(p.maxUtilization, 1e18 + 1, 2e18);
+    p.growthSpeed = _bound(p.growthSpeed, 1, 5e18);
+    (p.curveA, p.curveB) = boundCurve(
+      p.curveA,
+      uint256(p.curveB),
+      p.naturalUtilization,
+      p.maxUtilization,
+      p.growthSpeed
+    );
+    p.sigmoidSpeed = _bound(p.sigmoidSpeed, 1, 10e18);
+    p.maxRate = _bound(p.maxRate, 1, 15_000e16);
+    p.spreadFactor = _bound(p.spreadFactor, 1, 0.2e18); // TODO > 0.2e18; deviation sensitivity > 0.2e18
+    p.timePreference = _bound(p.timePreference, -0.1e18, 0.1e18); // deviation sensitivity > 0.1e18
+    p.maturitySpeed = _bound(p.maturitySpeed, 1, 5e18); // deviation sensitivity > 0.5e18
+
+    irm = new InterestRateModelHarness(
+      Market(address(0)),
+      p.curveA,
+      p.curveB,
+      p.maxUtilization,
+      p.naturalUtilization,
+      p.sigmoidSpeed,
+      p.growthSpeed,
+      p.maxRate,
+      p.spreadFactor,
+      p.timePreference,
+      p.maturitySpeed
+    );
 
     uint256 refRate;
-    if (uFixed > uGlobal || uFloating > uGlobal) {
-      vm.expectRevert(UtilizationExceeded.selector);
-    } else if (uGlobal >= 1e18) {
-      refRate = irm.maxRate();
+    if (uGlobal >= 1e18) {
+      refRate = p.maxRate;
     } else {
       string[] memory ffi = new string[](2);
       ffi[0] = "scripts/irm-fixed.sh";
       ffi[1] = encodeHex(
         abi.encode(
-          uFixed,
-          uGlobal,
-          irm.fixedNaturalUtilization(),
           irm.base(uFloating, uGlobal),
-          irm.maturitySpeed(),
-          irm.spreadFactor(),
-          irm.timePreference(),
-          maxPools,
+          1e18 - p.naturalUtilization,
+          p.spreadFactor,
+          p.timePreference,
+          p.maturitySpeed,
           maturity,
+          maxPools,
+          uFixed,
+          uGlobal,
           block.timestamp
         )
       );
       refRate = abi.decode(vm.ffi(ffi), (uint256));
-      if (refRate > irm.maxRate()) refRate = irm.maxRate();
+      if (refRate > p.maxRate) refRate = p.maxRate;
     }
     uint256 rate = irm.fixedRate(maturity, maxPools, uFixed, uFloating, uGlobal);
 
-    assertLe(rate, irm.maxRate(), "rate > maxRate");
-    assertApproxEqRel(rate, refRate, 1e12, "rate != expected");
+    assertLe(rate, p.maxRate, "rate > maxRate");
+    assertApproxEqRel(rate, refRate, 2e13, "rate != refRate");
   }
 
-  struct Vars {
-    uint256 rate;
-    uint256 refRate;
-    uint256 uFixed;
-    uint256 uFloating;
-    uint256 uGlobal;
-    uint256 backupBorrowed;
-    uint256 backupAmount;
-  }
-
-  function testFuzzReferenceLegacyFixedRate(
-    uint8 maturity,
-    uint32 floatingAssets,
-    uint32 floatingDebt,
-    uint32[2] memory fixedBorrows,
-    uint32[2] memory fixedDeposits,
-    uint32 amount
+  function testFuzzReferenceLegacyRateFixed(
+    uint256 maturity,
+    uint256 floatingAssets,
+    uint256 floatingDebt,
+    uint256[2] memory fixedBorrows,
+    uint256[2] memory fixedDeposits,
+    uint256 amount
   ) external {
-    maturity = uint8(_bound(maturity, 0, 1));
-    floatingDebt = uint32(_bound(floatingDebt, 0, floatingAssets));
-    fixedBorrows[0] = uint32(_bound(fixedBorrows[0], 0, floatingAssets - floatingDebt));
-    fixedBorrows[1] = uint32(_bound(fixedBorrows[1], 0, floatingAssets - floatingDebt - fixedBorrows[0]));
-    fixedDeposits[0] = uint32(_bound(fixedDeposits[0], 0, fixedBorrows[0]));
-    fixedDeposits[1] = uint32(_bound(fixedDeposits[1], 0, fixedBorrows[1]));
-    amount = uint32(_bound(amount, 0, floatingAssets - floatingDebt - fixedBorrows[0] - fixedBorrows[1]));
-
-    MockERC20 asset = new MockERC20("DAI", "DAI", 18);
+    maturity = _bound(maturity, 0, 1);
+    floatingDebt = _bound(floatingDebt, 0, floatingAssets);
+    fixedBorrows[0] = _bound(fixedBorrows[0], 0, floatingAssets - floatingDebt);
+    fixedBorrows[1] = _bound(fixedBorrows[1], 0, floatingAssets - floatingDebt - fixedBorrows[0]);
+    fixedDeposits[0] = _bound(fixedDeposits[0], 0, fixedBorrows[0]);
+    fixedDeposits[1] = _bound(fixedDeposits[1], 0, fixedBorrows[1]);
+    amount = _bound(amount, 0, floatingAssets - floatingDebt - fixedBorrows[0] - fixedBorrows[1]);
+
+    MockERC20 asset = new MockERC20("", "", 18);
     Market market = Market(
       address(new ERC1967Proxy(address(new Market(asset, Auditor(address(new MockAuditor())))), ""))
     );
@@ -236,6 +259,25 @@ contract InterestRateModelTest is Test {
     assertEq(v.rate, v.refRate, "rate != refRate");
   }
 
+  function boundCurve(
+    uint256 minRate,
+    uint256 maxNaturalRate,
+    uint256 naturalUtilization,
+    uint256 maxUtilization,
+    int256 growthSpeed
+  ) internal pure returns (uint256 curveA, int256 curveB) {
+    minRate = _bound(minRate, 0, 0.1e18);
+    maxNaturalRate = _bound(maxNaturalRate, minRate.mulWadDown(1.2e18), minRate.mulWadUp(2e18));
+
+    // curveA =
+    //   ((maxNaturalRate * (1e18 - 0.5e18 * naturalUtilization) ** growthSpeed - minRate) *
+    //     (maxUtilization - naturalUtilization) *
+    //     maxUtilization) /
+    //   naturalUtilization;
+    curveB = int256(minRate) - int256(curveA / maxUtilization);
+    return (1.2111e16, 2.5683e16);
+  }
+
   function encodeHex(bytes memory raw) internal pure returns (string memory) {
     bytes16 symbols = "0123456789abcdef";
     bytes memory buffer = new bytes(2 * raw.length + 2);
@@ -267,6 +309,23 @@ contract InterestRateModelTest is Test {
   function floatingUtilization(uint256 floatingAssets, uint256 floatingDebt) internal pure returns (uint256) {
     return floatingAssets > 0 ? floatingDebt.divWadUp(floatingAssets) : 0;
   }
+
+  function deployDefault() internal returns (InterestRateModelHarness) {
+    return
+      new InterestRateModelHarness(
+        Market(address(0)),
+        1.2111e16,
+        2.5683e16,
+        1.3e18,
+        0.75e18,
+        2.5e18,
+        1.1e18,
+        15_000e16,
+        0.2e18,
+        0.01e18,
+        0.5e18
+      );
+  }
 }
 
 contract MockAuditor {
@@ -282,7 +341,7 @@ contract InterestRateModelHarness is InterestRateModel {
     uint256 curveA_,
     int256 curveB_,
     uint256 maxUtilization_,
-    uint256 floatingNaturalUtilization_,
+    uint256 naturalUtilization_,
     int256 sigmoidSpeed_,
     int256 growthSpeed_,
     uint256 maxRate_,
@@ -295,7 +354,7 @@ contract InterestRateModelHarness is InterestRateModel {
       curveA_,
       curveB_,
       maxUtilization_,
-      floatingNaturalUtilization_,
+      naturalUtilization_,
       sigmoidSpeed_,
       growthSpeed_,
       maxRate_,
@@ -309,3 +368,36 @@ contract InterestRateModelHarness is InterestRateModel {
     return baseRate(uFloating, uGlobal);
   }
 }
+
+struct FloatingParameters {
+  uint256 curveA;
+  int256 curveB;
+  uint256 maxUtilization;
+  uint256 naturalUtilization;
+  int256 sigmoidSpeed;
+  int256 growthSpeed;
+  uint256 maxRate;
+}
+
+struct FixedParameters {
+  uint256 curveA;
+  int256 curveB;
+  uint256 maxUtilization;
+  uint256 naturalUtilization;
+  int256 sigmoidSpeed;
+  int256 growthSpeed;
+  uint256 maxRate;
+  int256 spreadFactor;
+  int256 timePreference;
+  int256 maturitySpeed;
+}
+
+struct Vars {
+  uint256 rate;
+  uint256 refRate;
+  uint256 uFixed;
+  uint256 uFloating;
+  uint256 uGlobal;
+  uint256 backupBorrowed;
+  uint256 backupAmount;
+}