4 files changed, 4 insertions, 12 deletions
diff --git a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
index 7997b1647..bd65c8eb3 100644
--- a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
@@ -52,8 +52,7 @@ export class ContractWrapper {
             throw new Error(ZeroExError.SubscriptionNotFound);
         }
         if (!_.isUndefined(err)) {
-            const callback = this._filterCallbacks[filterToken];
-            callback(err, undefined);
+            this._filterCallbacks[filterToken](err, undefined);
         }
         delete this._filters[filterToken];
         delete this._filterCallbacks[filterToken];
diff --git a/packages/0x.js/src/index.ts b/packages/0x.js/src/index.ts
index 1b3e893ba..e529e2858 100644
--- a/packages/0x.js/src/index.ts
+++ b/packages/0x.js/src/index.ts
@@ -6,8 +6,6 @@ export {
     ECSignature,
     ZeroExError,
     EventCallback,
-    EventCallbackAsync,
-    EventCallbackSync,
     ExchangeContractErrs,
     ContractEvent,
     Token,
diff --git a/packages/0x.js/src/order_watcher/event_watcher.ts b/packages/0x.js/src/order_watcher/event_watcher.ts
index 81529a98c..c39431f6d 100644
--- a/packages/0x.js/src/order_watcher/event_watcher.ts
+++ b/packages/0x.js/src/order_watcher/event_watcher.ts
@@ -81,7 +81,7 @@ export class EventWatcher {
                 ...log,
             };
             if (!_.isUndefined(this._intervalIdIfExists)) {
-                await callback(logEvent);
+                callback(logEvent);
             }
         }
     }
diff --git a/packages/0x.js/src/types.ts b/packages/0x.js/src/types.ts
index 11b5d8569..04dfe3b0d 100644
--- a/packages/0x.js/src/types.ts
+++ b/packages/0x.js/src/types.ts
@@ -42,13 +42,8 @@ export type OrderValues = [BigNumber, BigNumber, BigNumber,
 export type LogEvent = Web3.LogEntryEvent;
 export type DecodedLogEvent<ArgsType> = Web3.DecodedLogEntryEvent<ArgsType>;
 
-export type EventCallbackAsync<ArgsType> = (err: null|Error, log?: DecodedLogEvent<ArgsType>) => Promise<void>;
-export type EventCallbackSync<ArgsType> = (err: null|Error, log?: DecodedLogEvent<ArgsType>) => void;
-export type EventCallback<ArgsType> = EventCallbackSync<ArgsType>|EventCallbackAsync<ArgsType>;
-
-export type EventWatcherCallbackSync = (log: LogEvent) => void;
-export type EventWatcherCallbackAsync = (log: LogEvent) => Promise<void>;
-export type EventWatcherCallback = EventWatcherCallbackSync|EventWatcherCallbackAsync;
+export type EventCallback<ArgsType> = (err: null|Error, log?: DecodedLogEvent<ArgsType>) => void;
+export type EventWatcherCallback = (log: LogEvent) => void;
 
 export interface ExchangeContract extends Web3.ContractInstance {
     isValidSignature: {