diff --git a/libs/acn/PDU.cpp b/libs/acn/PDU.cpp
index 33e40f720..0fa3ef744 100644
--- a/libs/acn/PDU.cpp
+++ b/libs/acn/PDU.cpp
@@ -131,6 +131,11 @@ bool PDU::Pack(uint8_t *buffer, unsigned int *length) const {
  * Write this PDU to an OutputStream.
  */
 void PDU::Write(OutputStream *stream) const {
+  if (!stream) {
+    OLA_WARN << "PDU::Write: missing stream";
+    return;
+  }
+
   unsigned int size = Size();
 
   if (size <= TWOB_LENGTH_LIMIT && !m_force_length_flag) {
@@ -173,6 +178,11 @@ void PDU::Write(OutputStream *stream) const {
 void PDU::PrependFlagsAndLength(ola::io::OutputBufferInterface *output,
                                 uint8_t flags,
                                 bool force_length_flag) {
+  if (!output) {
+    OLA_WARN << "PDU::PrependFlagsAndLength: missing output";
+    return;
+  }
+
   PrependFlagsAndLength(output, output->Size(), flags, force_length_flag);
 }
 
@@ -184,6 +194,11 @@ void PDU::PrependFlagsAndLength(ola::io::OutputBufferInterface *output,
                                 unsigned int size,
                                 uint8_t flags,
                                 bool force_length_flag) {
+  if (!output) {
+    OLA_WARN << "PDU::PrependFlagsAndLength: missing output";
+    return;
+  }
+
   if (size + 2 <= TWOB_LENGTH_LIMIT && !force_length_flag) {
     size += 2;
     uint16_t flags_and_length = static_cast<uint16_t>(size);
diff --git a/libs/acn/PDU.h b/libs/acn/PDU.h
index 531a8e96b..18193c204 100644
--- a/libs/acn/PDU.h
+++ b/libs/acn/PDU.h
@@ -192,6 +192,11 @@ bool PDUBlock<C>::Pack(uint8_t *data, unsigned int *length) const {
  */
 template <class C>
 void PDUBlock<C>::Write(ola::io::OutputStream *stream) const {
+  if (!stream) {
+    OLA_WARN << "PDUBlock::Write: missing stream";
+    return;
+  }
+
   typename std::vector<const C*>::const_iterator iter;
   for (iter = m_pdus.begin(); iter != m_pdus.end(); ++iter) {
     // TODO(simon): optimize repeated headers & vectors here
diff --git a/libs/acn/PDUTest.cpp b/libs/acn/PDUTest.cpp
index fd6e9de05..cdeec1832 100644
--- a/libs/acn/PDUTest.cpp
+++ b/libs/acn/PDUTest.cpp
@@ -37,12 +37,14 @@ class PDUTest: public CppUnit::TestFixture {
   CPPUNIT_TEST_SUITE(PDUTest);
   CPPUNIT_TEST(testPDU);
   CPPUNIT_TEST(testPDUBlock);
+  CPPUNIT_TEST(testPDUToOutputStream);
   CPPUNIT_TEST(testBlockToOutputStream);
   CPPUNIT_TEST_SUITE_END();
 
  public:
     void testPDU();
     void testPDUBlock();
+    void testPDUToOutputStream();
     void testBlockToOutputStream();
 
     void setUp() {
@@ -136,6 +138,36 @@ void PDUTest::testPDUBlock() {
 }
 
 
+/*
+ * Test that writing a PDU to an OutputStream works.
+ */
+void PDUTest::testPDUToOutputStream() {
+  MockPDU pdu(0x1234, 0x2468);
+
+  IOQueue output;
+  OutputStream stream(&output);
+  pdu.Write(&stream);
+  OLA_ASSERT_EQ(14u, output.Size());
+
+  uint8_t *data = new uint8_t[output.Size()];
+  unsigned int data_size = output.Peek(data, output.Size());
+  OLA_ASSERT_EQ(output.Size(), data_size);
+
+  uint8_t EXPECTED[] = {
+    0x70, 0x0e, 0, 0,
+    0, 0x2b,
+    0x34, 0x12, 0, 0,
+    0x68, 0x24, 0, 0
+  };
+  OLA_ASSERT_DATA_EQUALS(EXPECTED, sizeof(EXPECTED), data, data_size);
+  output.Pop(output.Size());
+
+  // test null stream
+  pdu.Write(NULL);
+  delete[] data;
+}
+
+
 /*
  * Test that writing to an OutputStream works.
  */
@@ -164,6 +196,9 @@ void PDUTest::testBlockToOutputStream() {
   };
   OLA_ASSERT_DATA_EQUALS(EXPECTED, sizeof(EXPECTED), block_data, block_size);
   output.Pop(output.Size());
+
+  // test null stream
+  block.Write(NULL);
   delete[] block_data;
 }
 }  // namespace acn