diff --git a/src/Decoder.php b/src/Decoder.php
index 6bd07ef..3aa8eb7 100644
--- a/src/Decoder.php
+++ b/src/Decoder.php
@@ -99,6 +99,12 @@ public function pipe(WritableStreamInterface $dest, array $options = array())
     /** @internal */
     public function handleData($data)
     {
+
+        if (!\is_string($data)) {
+            $this->handleError(new \UnexpectedValueException('Expected stream to emit string, but got ' . \gettype($data)));
+            return;
+        }
+
         $this->buffer .= $data;
 
         // keep parsing while a newline has been found
diff --git a/tests/DecoderTest.php b/tests/DecoderTest.php
index 4e25b45..0743e6b 100644
--- a/tests/DecoderTest.php
+++ b/tests/DecoderTest.php
@@ -67,6 +67,14 @@ public function testEmitDataBigIntOptionWillForwardAsString()
         $this->input->emit('data', array("999888777666555444333222111000\n"));
     }
 
+    public function testEmitDataWithInvalidTypeWillForwardErrorWithUnexpectedValueException()
+    {
+        $this->decoder->on('data', $this->expectCallableNever());
+        $this->decoder->on('error', $this->expectCallableOnceWith($this->isInstanceOf('UnexpectedValueException')));
+
+        $this->input->emit('data', array(false));
+    }
+
     public function testEmitDataErrorWillForwardError()
     {
         $this->decoder->on('data', $this->expectCallableNever());