diff --git a/libs/acn/LLRPProbeRequestPDU.cpp b/libs/acn/LLRPProbeRequestPDU.cpp
index 6fe537808..ba1623ed3 100644
--- a/libs/acn/LLRPProbeRequestPDU.cpp
+++ b/libs/acn/LLRPProbeRequestPDU.cpp
@@ -56,7 +56,7 @@ void LLRPProbeRequestPDU::PrependPDU(ola::io::IOStack *stack,
                                          (known_uids.Size() * UID::LENGTH)));
   uint8_t vector = HostToNetwork(VECTOR_PROBE_REQUEST_DATA);
   stack->Write(reinterpret_cast<uint8_t*>(&vector), sizeof(vector));
-  PrependFlagsAndLength(stack);
+  PrependFlagsAndLength(stack, VFLAG_MASK | HFLAG_MASK | DFLAG_MASK, true);
 }
 }  // namespace acn
 }  // namespace ola
diff --git a/libs/acn/LLRPProbeRequestPDUTest.cpp b/libs/acn/LLRPProbeRequestPDUTest.cpp
index ca6596991..6666002b6 100644
--- a/libs/acn/LLRPProbeRequestPDUTest.cpp
+++ b/libs/acn/LLRPProbeRequestPDUTest.cpp
@@ -70,7 +70,7 @@ void LLRPProbeRequestPDUTest::testPrepend() {
   OLA_ASSERT(stack.Read(buffer, length));
 
   const uint8_t expected_data[] = {
-    0xf0, 0x23, 1,
+    0xf0, 0x00, 0x24, 1,
     0, 0, 0, 0, 0, 0,
     0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
     0x00, 0x00,