diff --git a/src/cfdp/pdu/mod.rs b/src/cfdp/pdu/mod.rs
index 6f03f32..d70bd50 100644
--- a/src/cfdp/pdu/mod.rs
+++ b/src/cfdp/pdu/mod.rs
@@ -1,4 +1,5 @@
 //! CFDP Packet Data Unit (PDU) support.
+use crate::cfdp::pdu::ack::InvalidAckedDirectiveCodeError;
 use crate::cfdp::*;
 use crate::crc::CRC_CCITT_FALSE;
 use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
@@ -85,6 +86,15 @@ pub enum PduError {
     TlvLv(#[from] TlvLvError),
 }
 
+impl From<InvalidAckedDirectiveCodeError> for PduError {
+    fn from(value: InvalidAckedDirectiveCodeError) -> Self {
+        Self::InvalidDirectiveType {
+            found: value.0 as u8,
+            expected: None,
+        }
+    }
+}
+
 pub trait WritablePduPacket {
     fn len_written(&self) -> usize;
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError>;