diff --git a/packages/codegen/src/templates/indexer-template.handlebars b/packages/codegen/src/templates/indexer-template.handlebars
index 589e6178..2eae5ad5 100644
--- a/packages/codegen/src/templates/indexer-template.handlebars
+++ b/packages/codegen/src/templates/indexer-template.handlebars
@@ -102,7 +102,7 @@ export class Indexer implements IndexerInterface {
   _abiMap: Map<string, JsonFragment[]>;
   _storageLayoutMap: Map<string, StorageLayout>;
   _contractMap: Map<string, ethers.utils.Interface>;
-  _eventSignaturesMap: Map<string, string[]>;
+  eventSignaturesMap: Map<string, string[]>;
 
   {{#if (subgraphPath)}}
   _entityTypesMap: Map<string, { [key: string]: string }>;
@@ -141,7 +141,7 @@ export class Indexer implements IndexerInterface {
     this._abiMap = new Map();
     this._storageLayoutMap = new Map();
     this._contractMap = new Map();
-    this._eventSignaturesMap = new Map();
+    this.eventSignaturesMap = new Map();
     let contractInterface: ethers.utils.Interface;
     let eventSignatures: string[];
     {{#each contracts as | contract |}}
@@ -159,7 +159,7 @@ export class Indexer implements IndexerInterface {
     eventSignatures = Object.values(contractInterface.events).map(value => {
       return contractInterface.getEventTopic(value);
     });
-    this._eventSignaturesMap.set(KIND_{{capitalize contract.contractName}}, eventSignatures);
+    this.eventSignaturesMap.set(KIND_{{capitalize contract.contractName}}, eventSignatures);
     {{#if contract.contractStorageLayout}}
 
     assert({{contract.contractName}}StorageLayout);
@@ -689,7 +689,7 @@ export class Indexer implements IndexerInterface {
   }
 
   async fetchEventsAndSaveBlocks (blocks: DeepPartial<BlockProgress>[]): Promise<{ blockProgress: BlockProgress, events: DeepPartial<Event>[] }[]> {
-    return this._baseIndexer.fetchEventsAndSaveBlocks(blocks, this._eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
+    return this._baseIndexer.fetchEventsAndSaveBlocks(blocks, this.eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
   }
 
   async fetchAndSaveFilteredEventsAndBlocks (startBlock: number, endBlock: number): Promise<{
@@ -698,11 +698,11 @@ export class Indexer implements IndexerInterface {
     ethFullBlock: EthFullBlock;
     ethFullTransactions: EthFullTransaction[];
   }[]> {
-    return this._baseIndexer.fetchAndSaveFilteredEventsAndBlocks(startBlock, endBlock, this._eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
+    return this._baseIndexer.fetchAndSaveFilteredEventsAndBlocks(startBlock, endBlock, this.eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
   }
 
   async fetchEventsForContracts (blockHash: string, blockNumber: number, addresses: string[]): Promise<DeepPartial<Event>[]> {
-    return this._baseIndexer.fetchEventsForContracts(blockHash, blockNumber, addresses, this._eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
+    return this._baseIndexer.fetchEventsForContracts(blockHash, blockNumber, addresses, this.eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
   }
 
   async saveBlockAndFetchEvents (block: DeepPartial<BlockProgress>): Promise<[
@@ -843,7 +843,7 @@ export class Indexer implements IndexerInterface {
     assert(blockHash);
     assert(blockNumber);
 
-    const { events: dbEvents, transactions } = await this._baseIndexer.fetchEvents(blockHash, blockNumber, this._eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
+    const { events: dbEvents, transactions } = await this._baseIndexer.fetchEvents(blockHash, blockNumber, this.eventSignaturesMap, this.parseEventNameAndArgs.bind(this));
 
     const dbTx = await this._db.createTransactionRunner();
     try {
diff --git a/packages/graph-node/src/watcher.ts b/packages/graph-node/src/watcher.ts
index 672473c8..7f1786c7 100644
--- a/packages/graph-node/src/watcher.ts
+++ b/packages/graph-node/src/watcher.ts
@@ -125,6 +125,21 @@ export class GraphWatcher {
 
       return acc;
     }, {});
+
+    this.fillEventSignatureMap();
+  }
+
+  fillEventSignatureMap () {
+    this._dataSources.forEach(contract => {
+      if (contract.kind === 'ethereum/contract' && contract.mapping.kind === 'ethereum/events') {
+        const contractName = contract.name;
+        const topicHashes = contract.mapping.eventHandlers.map((handler: any) => {
+          return this._dataSourceMap[contractName].contractInterface.getEventTopic(utils.EventFragment.from(handler.event).name);
+        });
+        assert(this._indexer);
+        this._indexer.eventSignaturesMap.set(contractName, topicHashes);
+      }
+    });
   }
 
   get dataSources (): any[] {
diff --git a/packages/graph-node/test/utils/indexer.ts b/packages/graph-node/test/utils/indexer.ts
index 110dc661..0987eeb5 100644
--- a/packages/graph-node/test/utils/indexer.ts
+++ b/packages/graph-node/test/utils/indexer.ts
@@ -27,6 +27,7 @@ import { GetStorageAt, getStorageValue, MappingKey, StorageLayout } from '@cerc-
 export class Indexer implements IndexerInterface {
   _getStorageAt: GetStorageAt;
   _storageLayoutMap: Map<string, StorageLayout> = new Map();
+  eventSignaturesMap: Map<string, string[]> = new Map();
 
   constructor (ethClient: EthClient, storageLayoutMap?: Map<string, StorageLayout>) {
     this._getStorageAt = ethClient.getStorageAt.bind(ethClient);
diff --git a/packages/util/src/types.ts b/packages/util/src/types.ts
index 13f76dfb..1e899cc4 100644
--- a/packages/util/src/types.ts
+++ b/packages/util/src/types.ts
@@ -156,6 +156,7 @@ export interface EthClient {
 }
 
 export interface IndexerInterface {
+  eventSignaturesMap: Map<string, string[]>
   readonly serverConfig: ServerConfig
   readonly upstreamConfig: UpstreamConfig
   readonly storageLayoutMap: Map<string, StorageLayout>