diff --git a/contracts/TokenDelegator.sol b/contracts/TokenDelegator.sol
index 7618e91..5efad45 100644
--- a/contracts/TokenDelegator.sol
+++ b/contracts/TokenDelegator.sol
@@ -12,6 +12,7 @@ contract TokenDelegator is TokenDelegatorStorage, TokenEvents {
         uint changeImplementationAfter_,
         bool transferPaused_
     ) {
+        require(implementation_ != address(0), "TokenDelegator::constructor invalid address");
         delegateTo(
             implementation_,
             abi.encodeWithSignature(