Fallback function has to be external: backwards-compatible changes.

test/compilationTests/zeppelin/Bounty.sol

@@ -18,7 +18,7 @@ contract Bounty is PullPayment, Destructible {
   /**
    * @dev Fallback function allowing the contract to recieve funds, if they haven't already been claimed.
    */
-  function() payable {
+  function() external payable {
     if (claimed) {
       throw;
     }

test/compilationTests/zeppelin/MultisigWallet.sol

@@ -39,7 +39,7 @@ contract MultisigWallet is Multisig, Shareable, DayLimit {
   /** 
    * @dev Fallback function, receives value and emits a deposit event. 
    */
-  function() payable {
+  function() external payable {
     // just being sent some cash?
     if (msg.value > 0)
       emit Deposit(msg.sender, msg.value);

test/compilationTests/zeppelin/crowdsale/Crowdsale.sol

@@ -61,7 +61,7 @@ contract Crowdsale {
 
 
   // fallback function can be used to buy tokens
-  function () payable {
+  function () external payable {
     buyTokens(msg.sender);
   }