diff --git a/src/WrappedMToken.sol b/src/WrappedMToken.sol
index e76347b..8702c13 100644
--- a/src/WrappedMToken.sol
+++ b/src/WrappedMToken.sol
@@ -40,7 +40,7 @@ contract WrappedMToken is IWrappedMToken, Migratable, ERC20Extended {
     mapping(address account => BalanceInfo balance) internal _balances;
 
     modifier onlyWhenEarning() {
-        if (IMTokenLike(mToken).isEarning(address(this))) revert NotInEarningState();
+        if (!IMTokenLike(mToken).isEarning(address(this))) revert NotInEarningState();
 
         _;
     }
@@ -56,7 +56,7 @@ contract WrappedMToken is IWrappedMToken, Migratable, ERC20Extended {
 
     /* ============ Interactive Functions ============ */
 
-    function wrap(address recipient_, uint256 amount_) external onlyWhenEarning {
+    function wrap(address recipient_, uint256 amount_) external {
         _mint(recipient_, UIntMath.safe240(amount_));
 
         IMTokenLike(mToken).transferFrom(msg.sender, address(this), amount_);
@@ -78,7 +78,19 @@ contract WrappedMToken is IWrappedMToken, Migratable, ERC20Extended {
         IMTokenLike(mToken).transfer(vault, yield_);
     }
 
-    function startEarningFor(address account_) external {
+    function startEarningM() external {
+        if (mIndexWhenEarningStopped != 0) revert OnlyEarningOnce();
+
+        IMTokenLike(mToken).startEarning();
+    }
+
+    function stopEarningM() external {
+        mIndexWhenEarningStopped = currentIndex();
+
+        IMTokenLike(mToken).stopEarning();
+    }
+
+    function startEarningFor(address account_) external onlyWhenEarning {
         if (!_isApprovedEarner(account_)) revert NotApprovedEarner();
 
         (bool isEarning_, , , uint240 balance_) = _getBalanceInfo(account_);
@@ -118,18 +130,6 @@ contract WrappedMToken is IWrappedMToken, Migratable, ERC20Extended {
         }
     }
 
-    function startEarningM() external {
-        if (mIndexWhenEarningStopped != 0) revert OnlyEarningOnce();
-
-        IMTokenLike(mToken).startEarning();
-    }
-
-    function stopEarningM() external {
-        mIndexWhenEarningStopped = currentIndex();
-
-        IMTokenLike(mToken).stopEarning();
-    }
-
     /* ============ View/Pure Functions ============ */
 
     function accruedYieldOf(address account_) external view returns (uint240 yield_) {
diff --git a/test/Test.t.sol b/test/Test.t.sol
index 166ecf7..a04108c 100644
--- a/test/Test.t.sol
+++ b/test/Test.t.sol
@@ -72,6 +72,8 @@ contract Tests is Test {
         _registrar.setListContains(_EARNERS_LIST, _alice, true);
         _registrar.setListContains(_EARNERS_LIST, _bob, true);
 
+        _wrappedMToken.startEarningM();
+
         _wrappedMToken.startEarningFor(_alice);
 
         _wrappedMToken.startEarningFor(_bob);
diff --git a/test/WrappedMToken.t.sol b/test/WrappedMToken.t.sol
index 56eec8f..7f7a7b7 100644
--- a/test/WrappedMToken.t.sol
+++ b/test/WrappedMToken.t.sol
@@ -54,6 +54,8 @@ contract WrappedMTokenTests is Test {
         _wrappedMToken = WrappedMTokenHarness(address(new Proxy(address(_implementation))));
 
         _mToken.setCurrentIndex(_currentIndex = 1_100000068703);
+
+        _wrappedMToken.startEarningM();
     }
 
     /* ============ constructor ============ */
@@ -430,6 +432,31 @@ contract WrappedMTokenTests is Test {
         assertEq(_wrappedMToken.totalEarningSupply(), 1); // TODO: Fix?
     }
 
+    /* ============ startEarningM ============ */
+    function test_startEarningM_onlyEarningOnce() external {
+        assertEq(_mToken.isEarning(address(_wrappedMToken)), true);
+
+        _wrappedMToken.stopEarningM();
+
+        vm.expectRevert(IWrappedMToken.OnlyEarningOnce.selector);
+        _wrappedMToken.startEarningM();
+    }
+
+    /* ============ stopEarningM ============ */
+    function test_stopEarningM() external {
+        assertEq(_mToken.isEarning(address(_wrappedMToken)), true);
+        assertEq(_wrappedMToken.mIndexWhenEarningStopped(), 0);
+
+        _wrappedMToken.stopEarningM();
+
+        assertEq(_mToken.isEarning(address(_wrappedMToken)), false);
+        assertEq(_wrappedMToken.mIndexWhenEarningStopped(), _mToken.currentIndex());
+
+        _mToken.setCurrentIndex(_currentIndex = _EXP_SCALED_ONE);
+
+        assertEq(_wrappedMToken.currentIndex(), _wrappedMToken.mIndexWhenEarningStopped());
+    }
+
     /* ============ balanceOf ============ */
     function test_balanceOf_nonEarner() external {
         _wrappedMToken.setBalanceOf(_alice, 500);
diff --git a/test/utils/Mocks.sol b/test/utils/Mocks.sol
index 87dda4d..b3c7833 100644
--- a/test/utils/Mocks.sol
+++ b/test/utils/Mocks.sol
@@ -8,12 +8,13 @@ contract MockM {
     uint128 public currentIndex;
 
     mapping(address account => uint256 balance) public balanceOf;
+    mapping(address account => bool isEarning) public isEarning;
 
-    function transfer(address, uint256) external returns (bool success_) {
+    function transfer(address, uint256) external pure returns (bool success_) {
         return true;
     }
 
-    function transferFrom(address, address, uint256) external returns (bool success_) {
+    function transferFrom(address, address, uint256) external pure returns (bool success_) {
         return true;
     }
 
@@ -28,6 +29,14 @@ contract MockM {
     function setTtgRegistrar(address ttgRegistrar_) external {
         ttgRegistrar = ttgRegistrar_;
     }
+
+    function startEarning() external {
+        isEarning[msg.sender] = true;
+    }
+
+    function stopEarning() external {
+        isEarning[msg.sender] = false;
+    }
 }
 
 contract MockRegistrar {