diff --git a/contracts/libraries/UQ104x104.sol b/contracts/libraries/UQ104x104.sol
index 0df0926..26d0e8b 100644
--- a/contracts/libraries/UQ104x104.sol
+++ b/contracts/libraries/UQ104x104.sol
@@ -1,17 +1,16 @@
 pragma solidity 0.5.12;
 
-// TODO this whole library is basically just a mock at the moment
+// TODO this library is broken at the moment, and is meant only to serve as a mock
 library UQ104x104 {
     uint208 constant Q104 = uint104(-1);
 
     function encode(uint128 y) internal pure returns (uint208 z) {
-        // require(y <= Q104, "encode-overflow");
+        require(y <= Q104, "encode-overflow");
         z = y * Q104;
     }
-    function qmul(uint208 x, uint208 y) internal pure returns (uint208 z) {
-        z = x * y / Q104;
-    }
     function qdiv(uint208 x, uint208 y) internal pure returns (uint208 z) {
-        z = x / y;
+        uint256 quotient = uint256(x) / uint256(y);
+        require(quotient <= Q104, "div-overflow");
+        z = uint208(quotient * Q104);
     }
 }
diff --git a/contracts/test/GenericERC20.sol b/contracts/test/GenericERC20.sol
deleted file mode 100644
index 8981525..0000000
--- a/contracts/test/GenericERC20.sol
+++ /dev/null
@@ -1,12 +0,0 @@
-pragma solidity 0.5.12;
-
-import "../token/ERC20.sol";
-
-contract GenericERC20 is ERC20 {
-    constructor(
-        string memory _name,
-        string memory _symbol,
-        uint8 _decimals,
-        uint256 _totalSupply
-    ) ERC20(_name, _symbol, _decimals, _totalSupply) public {}
-}