diff --git a/src/Dubture/Monolog/Reader/LogReader.php b/src/Dubture/Monolog/Reader/LogReader.php
index 6084596..c20deb6 100644
--- a/src/Dubture/Monolog/Reader/LogReader.php
+++ b/src/Dubture/Monolog/Reader/LogReader.php
@@ -69,7 +69,7 @@ public function setParser(LogParserInterface $parser)
      */
     public function offsetExists($offset)
     {
-        return $this->lineCount >= $offset;
+        return $offset < $this->lineCount;
     }
 
     /**
diff --git a/tests/Dubture/Monolog/Reader/Test/LogReaderTest.php b/tests/Dubture/Monolog/Reader/Test/LogReaderTest.php
index 8938177..8b22e4c 100644
--- a/tests/Dubture/Monolog/Reader/Test/LogReaderTest.php
+++ b/tests/Dubture/Monolog/Reader/Test/LogReaderTest.php
@@ -45,11 +45,18 @@ public function testReader()
 
     public function testIterator()
     {
+        // the test.log file contains 2 log lines
         $file = __DIR__ . '/../../../../files/test.log';
         $reader = new LogReader($file);
         $lines = array();
         $keys = array();
 
+        $this->assertTrue($reader->offsetExists(0));
+        $this->assertTrue($reader->offsetExists(1));
+
+        $this->assertFalse($reader->offsetExists(2));
+        $this->assertFalse($reader->offsetExists(3));
+
         $this->assertEquals(2, count($reader));
 
         foreach ($reader as $i => $log) {