diff --git a/Hash2Pub/FediChord.asn1 b/Hash2Pub/FediChord.asn1
index e2a7ab5..7c53cb0 100644
--- a/Hash2Pub/FediChord.asn1
+++ b/Hash2Pub/FediChord.asn1
@@ -18,7 +18,7 @@ Request ::= SEQUENCE {
 		leaveRequestPayload		LeaveRequestPayload,
 		stabiliseRequestPayload	StabiliseRequestPayload,
 		pingRequestPayload			PingRequestPayload
-		}
+		}			OPTIONAL			-- just for symmetry reasons with response, requests without a payload have no meaning
 	}
 
 -- idea: different message layouts as a way of distinguishing between
@@ -36,7 +36,7 @@ Response ::= SEQUENCE {
 		leaveResponsePayload		LeaveResponsePayload,
 		stabiliseResponsePayload	StabiliseResponsePayload,
 		pingResponsePayload		PingResponsePayload
-		}
+		}			OPTIONAL			-- no payload when just ACKing a previous request
 	}
 
 NodeState ::= SEQUENCE {
diff --git a/Hash2Pub/src/Hash2Pub/ASN1Coding.hs b/Hash2Pub/src/Hash2Pub/ASN1Coding.hs
index 47d91f1..ed20e1d 100644
--- a/Hash2Pub/src/Hash2Pub/ASN1Coding.hs
+++ b/Hash2Pub/src/Hash2Pub/ASN1Coding.hs
@@ -215,7 +215,7 @@ encodeMessage
       ++ [
         IntVal parts
       , IntVal part ]
-      ++ encodePayload requestPayload
+      ++ maybe [] encodePayload requestPayload
       ++ [End Sequence]
 encodeMessage
     (Response responseTo senderID parts part action responsePayload) = [
@@ -225,7 +225,7 @@ encodeMessage
       , IntVal parts
       , IntVal part
       , Enumerated . fromIntegral . fromEnum $ action]
-      ++ encodePayload responsePayload
+      ++ maybe [] encodePayload responsePayload
       ++ [End Sequence]
 
 -- ===== parser combinators =====
@@ -258,7 +258,8 @@ parseRequest action = do
     sender <- parseNodeState
     parts <- parseInteger
     part <- parseInteger
-    payload <- case action of
+    hasPayload <- hasNext
+    payload <- if not hasPayload then return Nothing else Just <$> case action of
                  QueryID -> parseQueryIDRequest
                  Join -> parseJoinRequest
                  Leave -> parseLeaveRequest
@@ -273,7 +274,8 @@ parseResponse responseTo = do
     parts <- parseInteger
     part <- parseInteger
     action <- parseEnum :: ParseASN1 Action
-    payload <- case action of
+    hasPayload <- hasNext
+    payload <- if not hasPayload then return Nothing else Just <$> case action of
                  QueryID -> parseQueryIDResponse
                  Join -> parseJoinResponse
                  Leave -> parseLeaveResponse
diff --git a/Hash2Pub/src/Hash2Pub/DHTProtocol.hs b/Hash2Pub/src/Hash2Pub/DHTProtocol.hs
index f61cfd8..d02b312 100644
--- a/Hash2Pub/src/Hash2Pub/DHTProtocol.hs
+++ b/Hash2Pub/src/Hash2Pub/DHTProtocol.hs
@@ -97,7 +97,7 @@ data FediChordMessage =
   , part            :: Integer
   -- ^ part starts at 0
   , action          :: Action
-  , payload         :: ActionPayload
+  , payload         :: Maybe ActionPayload
                         }
   | Response {
     responseTo      :: Integer
@@ -105,7 +105,7 @@ data FediChordMessage =
   , parts           :: Integer
   , part            :: Integer
   , action          :: Action
-  , payload         :: ActionPayload
+  , payload         :: Maybe ActionPayload
              } deriving (Show, Eq)
 
 data ActionPayload = 
diff --git a/Hash2Pub/test/FediChordSpec.hs b/Hash2Pub/test/FediChordSpec.hs
index 363aa54..e72b516 100644
--- a/Hash2Pub/test/FediChordSpec.hs
+++ b/Hash2Pub/test/FediChordSpec.hs
@@ -212,8 +212,8 @@ spec = do
               , action = undefined
               , payload = undefined
                                       }
-            requestWith a pa = requestTemplate {action = a, payload = pa}
-            responseWith a pa = responseTemplate {action = a, payload = pa}
+            requestWith a pa = requestTemplate {action = a, payload = Just pa}
+            responseWith a pa = responseTemplate {action = a, payload = Just pa}
 
             encodeDecodeAndCheck msg = runParseASN1 parseMessage (encodeMessage msg) `shouldBe` pure msg
         it "messages are encoded and decoded correctly from and to ASN1" $ do