diff --git a/logstash-core/benchmarks/src/main/java/org/logstash/benchmark/BufferedTokenizerExtBenchmark.java b/logstash-core/benchmarks/src/main/java/org/logstash/benchmark/BufferedTokenizerExtBenchmark.java
index 024ecf442a3..5b01cebb3e5 100644
--- a/logstash-core/benchmarks/src/main/java/org/logstash/benchmark/BufferedTokenizerExtBenchmark.java
+++ b/logstash-core/benchmarks/src/main/java/org/logstash/benchmark/BufferedTokenizerExtBenchmark.java
@@ -12,7 +12,6 @@
 import org.openjdk.jmh.annotations.Level;
 import org.openjdk.jmh.annotations.Measurement;
 import org.openjdk.jmh.annotations.Mode;
-import org.openjdk.jmh.annotations.OperationsPerInvocation;
 import org.openjdk.jmh.annotations.OutputTimeUnit;
 import org.openjdk.jmh.annotations.Scope;
 import org.openjdk.jmh.annotations.Setup;
diff --git a/logstash-core/spec/logstash/util/buftok_spec.rb b/logstash-core/spec/logstash/util/buftok_spec.rb
index acdf2097709..3d7b4b1990f 100644
--- a/logstash-core/spec/logstash/util/buftok_spec.rb
+++ b/logstash-core/spec/logstash/util/buftok_spec.rb
@@ -61,6 +61,11 @@
     context 'with decode_size_limit_bytes' do
       subject { FileWatch::BufferedTokenizer.new("\n", 100) }
 
+      it "validates size limit" do
+        expect { FileWatch::BufferedTokenizer.new("\n", -101) }.to raise_error(java.lang.IllegalArgumentException, "Size limit must be positive")
+        expect { FileWatch::BufferedTokenizer.new("\n", 0) }.to raise_error(java.lang.IllegalArgumentException, "Size limit must be positive")
+      end
+
       it "emits the contents of the buffer" do
         expect(subject.flush).to eq(data)
       end
diff --git a/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java b/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
index f704fcb0f7f..be1c64d2356 100644
--- a/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
+++ b/logstash-core/src/main/java/org/logstash/common/BufferedTokenizerExt.java
@@ -55,7 +55,11 @@ public IRubyObject init(final ThreadContext context, IRubyObject[] args) {
             this.delimiter = args[0].convertToString();
         }
         if (args.length == 2) {
-            this.sizeLimit = args[1].convertToInteger().getIntValue();
+            final int sizeLimit = args[1].convertToInteger().getIntValue();
+            if (sizeLimit <= 0) {
+                throw new IllegalArgumentException("Size limit must be positive");
+            }
+            this.sizeLimit = sizeLimit;
             this.hasSizeLimit = true;
         }
         this.inputSize = 0;