diff --git a/.gitignore b/.gitignore
index ad46b30..5123e7e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -59,3 +59,6 @@ typings/
 
 # next.js build output
 .next
+
+# VSCode
+.vscode/
diff --git a/lib/aws-wrappers.js b/lib/aws-wrappers.js
index 9f3d253..093e0cc 100644
--- a/lib/aws-wrappers.js
+++ b/lib/aws-wrappers.js
@@ -10,7 +10,7 @@ class FirehoseWrapper {
 
 	/* istanbul ignore next */
 	// AWS generates the Firehose class on the fly, the putRecord method do not exists before creating the insance
-	async putRecord(record) {
+	putRecord(record) {
 		return this._firehose.putRecord(record).promise();
 	}
 }
@@ -23,7 +23,7 @@ class StsWrapper {
 
 	/* istanbul ignore next */
 	// AWS generates the STS class on the fly, the assumeRole method do not exists before creating the insance
-	async assumeRole(params) {
+	assumeRole(params) {
 		return this._sts.assumeRole(params).promise();
 	}
 }
diff --git a/lib/log-error.js b/lib/log-error.js
index 81f83bd..4fd30fe 100644
--- a/lib/log-error.js
+++ b/lib/log-error.js
@@ -7,7 +7,8 @@ class LogError extends Error {
 		return {
 			INVALID_LOG: 1,
 			FIREHOSE_ERROR: 2,
-			NO_ENVIRONMENT: 3
+			NO_ENVIRONMENT: 3,
+			ASSUME_ROLE_ERROR: 4
 		};
 
 	}
diff --git a/lib/log.js b/lib/log.js
index 124c234..0d931ac 100644
--- a/lib/log.js
+++ b/lib/log.js
@@ -150,12 +150,17 @@ class Log {
 
 	static async _getCredentials() {
 
-		const { Credentials, Expiration } = await sts.assumeRole({
+		const assumedRole = await sts.assumeRole({
 			RoleArn: this._roleArn,
 			RoleSessionName: this._serviceName,
 			DurationSeconds: ARN_DURATION
 		});
 
+		if(!assumedRole)
+			throw new LogError('Failed to assume role, invalid response.', LogError.codes.ASSUME_ROLE_ERROR);
+
+		const { Credentials, Expiration } = assumedRole;
+
 		return {
 			accessKeyId: Credentials.AccessKeyId,
 			secretAccessKey: Credentials.SecretAccessKey,
@@ -174,10 +179,10 @@ class Log {
 
 	static async _add(log, attempts = 0) {
 
-		const firehose = await this._getFirehoseInstance();
-
 		try {
 
+			const firehose = await this._getFirehoseInstance();
+
 			await firehose.putRecord({
 				DeliveryStreamName: this.deliveryStreamName,
 				Record: {
diff --git a/tests/log-test.js b/tests/log-test.js
index b07b8c0..12ae1a9 100644
--- a/tests/log-test.js
+++ b/tests/log-test.js
@@ -245,6 +245,30 @@ describe('Log', () => {
 			sandbox.assert.notCalled(Firehose.prototype.putRecord);
 		});
 
+		it('Should not call Firehose putRecord when assume role rejects', async () => {
+
+			sandbox.stub(STS.prototype, 'assumeRole')
+				.rejects();
+
+			sandbox.spy(Firehose.prototype, 'putRecord');
+
+			await Log.add('some-client', fakeLog);
+
+			sandbox.assert.notCalled(Firehose.prototype.putRecord);
+		});
+
+		it('Should not call Firehose putRecord when assume role returns an invalid result', async () => {
+
+			sandbox.stub(STS.prototype, 'assumeRole')
+				.resolves(null);
+
+			sandbox.spy(Firehose.prototype, 'putRecord');
+
+			await Log.add('some-client', fakeLog);
+
+			sandbox.assert.notCalled(Firehose.prototype.putRecord);
+		});
+
 		it('Should emit an error when something goes wrong', async () => {
 
 			let errorEmitted = false;