diff --git a/.travis.yml b/.travis.yml
index ce6e007..0592b1e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,8 +6,10 @@ jdk: oraclejdk8
 rvm:
   - jruby-1.7.25
 env:
-  - KAFKA_VERSION=0.10.0.1
-before_install: ./kafka_test_setup.sh
+  - KAFKA_VERSION=0.10.2.2
+before_install:
+  - gem install bundler -v '< 2'
+  - ./kafka_test_setup.sh
 before_script:
   - bundle exec rake vendor
 script: bundle exec rspec && bundle exec rspec --tag integration
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c23a609..3fcb468 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 5.1.12
+  - Backport of fixes from more recent branches:
+    - Fixed incorrect millisecond to second conversion for retry_backoff_ms [#216](https://github.com/logstash-plugins/logstash-output-kafka/pull/216)
+    - Fixed unnecessary sleep after exhausted retries [#166](https://github.com/logstash-plugins/logstash-output-kafka/pull/166)
+    - Changed Kafka send errors to log as warn [#179](https://github.com/logstash-plugins/logstash-output-kafka/pull/179)
+
 ## 5.1.11
   - Bugfix: Sends are now retried until successful. Previously, failed transmissions to Kafka 
     could have been lost by the KafkaProducer library. Now we verify transmission explicitly.
diff --git a/kafka_test_setup.sh b/kafka_test_setup.sh
index 771fb17..b9abdfa 100755
--- a/kafka_test_setup.sh
+++ b/kafka_test_setup.sh
@@ -5,7 +5,7 @@ set -ex
 if [ -n "${KAFKA_VERSION+1}" ]; then
   echo "KAFKA_VERSION is $KAFKA_VERSION"
 else
-   KAFKA_VERSION=0.10.1.0
+   KAFKA_VERSION=0.10.2.2
 fi
 
 echo "Downloading Kafka version $KAFKA_VERSION"
diff --git a/lib/logstash/outputs/kafka.rb b/lib/logstash/outputs/kafka.rb
index e4d29f7..02dd9a8 100644
--- a/lib/logstash/outputs/kafka.rb
+++ b/lib/logstash/outputs/kafka.rb
@@ -234,7 +234,7 @@ def multi_receive(events)
   end
 
   def retrying_send(batch)
-    remaining = @retries;
+    remaining = @retries
 
     while batch.any?
       if !remaining.nil?
@@ -275,7 +275,7 @@ def retrying_send(batch)
           result = future.get()
         rescue => e
           # TODO(sissel): Add metric to count failures, possibly by exception type.
-          logger.debug? && logger.debug("KafkaProducer.send() failed: #{e}", :exception => e);
+          logger.warn("KafkaProducer.send() failed: #{e}", :exception => e)
           failures << batch[i]
         end
       end
@@ -284,13 +284,15 @@ def retrying_send(batch)
       break if failures.empty?
 
       # Otherwise, retry with any failed transmissions
-      batch = failures
-      delay = 1.0 / @retry_backoff_ms
-      logger.info("Sending batch to Kafka failed. Will retry after a delay.", :batch_size => batch.size,
-                  :failures => failures.size, :sleep => delay);
-      sleep(delay)
+      if remaining.nil? || remaining >= 0
+        delay = @retry_backoff_ms / 1000.0
+        logger.info("Sending batch to Kafka failed. Will retry after a delay.", :batch_size => batch.size,
+                                                                                :failures => failures.size,
+                                                                                :sleep => delay)
+        batch = failures
+        sleep(delay)
+      end
     end
-
   end
 
   def close
diff --git a/spec/unit/outputs/kafka_spec.rb b/spec/unit/outputs/kafka_spec.rb
index 7041a45..2d99a05 100644
--- a/spec/unit/outputs/kafka_spec.rb
+++ b/spec/unit/outputs/kafka_spec.rb
@@ -49,7 +49,7 @@
       kafka.register
       kafka.multi_receive([event])
     end
-    
+
     it 'should raise config error when truststore location is not set and ssl is enabled' do
       kafka = LogStash::Outputs::Kafka.new(simple_kafka_config.merge("security_protocol" => "SSL"))
       expect { kafka.register }.to raise_error(LogStash::ConfigurationError, /ssl_truststore_location must be set when SSL is enabled/)
@@ -120,6 +120,41 @@
       end
     end
 
+    context 'when retries is 0' do
+      let(:retries) { 0  }
+      let(:max_sends) { 1 }
+
+      it "should should only send once" do
+        expect_any_instance_of(org.apache.kafka.clients.producer.KafkaProducer).to receive(:send)
+                                                                                       .once
+                                                                                       .and_wrap_original do |m, *args|
+          # Always fail.
+          future = java.util.concurrent.FutureTask.new { raise "Failed" }
+          future.run
+          future
+        end
+        kafka = LogStash::Outputs::Kafka.new(simple_kafka_config.merge("retries" => retries))
+        kafka.register
+        kafka.multi_receive([event])
+      end
+
+      it 'should not sleep' do
+        expect_any_instance_of(org.apache.kafka.clients.producer.KafkaProducer).to receive(:send)
+                                                                                       .once
+                                                                                       .and_wrap_original do |m, *args|
+          # Always fail.
+          future = java.util.concurrent.FutureTask.new { raise "Failed" }
+          future.run
+          future
+        end
+
+        kafka = LogStash::Outputs::Kafka.new(simple_kafka_config.merge("retries" => retries))
+        expect(kafka).not_to receive(:sleep).with(anything)
+        kafka.register
+        kafka.multi_receive([event])
+      end
+    end
+
     context "and when retries is set by the user" do
       let(:retries) { (rand * 10).to_i }
       let(:max_sends) { retries + 1 }
@@ -137,6 +172,21 @@
         kafka.register
         kafka.multi_receive([event])
       end
+
+      it 'should only sleep retries number of times' do
+        expect_any_instance_of(org.apache.kafka.clients.producer.KafkaProducer).to receive(:send)
+                                                                                       .at_most(max_sends)
+                                                                                       .and_wrap_original do |m, *args|
+          # Always fail.
+          future = java.util.concurrent.FutureTask.new { raise "Failed" }
+          future.run
+          future
+        end
+        kafka = LogStash::Outputs::Kafka.new(simple_kafka_config.merge("retries" => retries))
+        expect(kafka).to receive(:sleep).exactly(retries).times
+        kafka.register
+        kafka.multi_receive([event])
+      end
     end
   end
 end