diff --git a/contracts/CToken.sol b/contracts/CToken.sol
index 719918e88..6491d1ca4 100644
--- a/contracts/CToken.sol
+++ b/contracts/CToken.sol
@@ -470,7 +470,7 @@ contract CToken is CTokenInterface, Exponential, TokenErrorReporter {
         emit AccrueInterest(cashPrior, interestAccumulated, borrowIndexNew, totalBorrowsNew);
 
         // Attempt to add interest checkpoint
-        address(interestRateModel).call(abi.encodeWithSignature("checkpointInterest(uint256)", borrowRateMantissa));
+        if (interestRateModelReactive) address(interestRateModel).call(abi.encodeWithSignature("checkpointInterest(uint256)", borrowRateMantissa));
 
         return uint(Error.NO_ERROR);
     }
@@ -1503,10 +1503,11 @@ contract CToken is CTokenInterface, Exponential, TokenErrorReporter {
         emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);
 
         // Attempt to reset interest checkpoints on old IRM
-        if (address(oldInterestRateModel) != address(0)) address(oldInterestRateModel).call(abi.encodeWithSignature("resetInterestCheckpoints()"));
+        if (interestRateModelReactive) address(oldInterestRateModel).call(abi.encodeWithSignature("resetInterestCheckpoints()"));
 
         // Attempt to add first interest checkpoint on new IRM
-        address(newInterestRateModel).call(abi.encodeWithSignature("checkpointInterest()"));
+        (bool success, ) = address(newInterestRateModel).call(abi.encodeWithSignature("checkpointInterest()"));
+        interestRateModelReactive = success;
 
         return uint(Error.NO_ERROR);
     }
diff --git a/contracts/CTokenInterfaces.sol b/contracts/CTokenInterfaces.sol
index 3caeb60be..2b48dfa4a 100644
--- a/contracts/CTokenInterfaces.sol
+++ b/contracts/CTokenInterfaces.sol
@@ -157,6 +157,16 @@ contract CTokenStorage is CTokenAdminStorage {
      * @notice Share of seized collateral that is added to reserves
      */
     uint public constant protocolSeizeShareMantissa = 2.8e16; //2.8%
+
+    /**
+     * @notice Underlying asset for this CToken
+     */
+    address public underlying;
+
+    /**
+     * @notice Whether or not the interestRateModel is reactive.
+     */
+    bool public interestRateModelReactive;
 }
 
 contract CTokenInterface is CTokenStorage {
@@ -284,15 +294,7 @@ contract CTokenInterface is CTokenStorage {
     function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint);
 }
 
-contract CErc20Storage {
-    /**
-     * @notice Underlying asset for this CToken
-     */
-    address public underlying;
-}
-
-contract CErc20Interface is CErc20Storage {
-
+contract CErc20Interface {
     /*** User Interface ***/
 
     function mint(uint mintAmount) external returns (uint);
@@ -302,10 +304,9 @@ contract CErc20Interface is CErc20Storage {
     function repayBorrow(uint repayAmount) external returns (uint);
     function repayBorrowBehalf(address borrower, uint repayAmount) external returns (uint);
     function liquidateBorrow(address borrower, uint repayAmount, CTokenInterface cTokenCollateral) external returns (uint);
-
 }
 
-contract CEtherInterface is CErc20Storage {
+contract CEtherInterface {
     /**
      * @notice Indicator that this is a CEther contract (for inspection)
      */