diff --git a/lib/message-parser.js b/lib/message-parser.js
index 414ad1e..3f69061 100644
--- a/lib/message-parser.js
+++ b/lib/message-parser.js
@@ -118,14 +118,19 @@ class MessageParser {
     // Check for extra data
     let leftover = false;
 
-    let suffixLocation = buffer.indexOf('0000AA55', 0, 'hex');
-    if (suffixLocation === -1) {// Couldn't find 0000AA55 during parse
-      suffixLocation = buffer.indexOf('00009966', 0, 'hex');
+    // Frame end comes from the length field: a search for the suffix bytes
+    // also matches a sequence number or ciphertext holding those bytes
+    const frameLength = prefix === 0x00006699 ?
+      buffer.readUInt32BE(14) + 22 : // Header (18) + length + suffix (4)
+      buffer.readUInt32BE(12) + 16; // Header (16) + length
+
+    if (buffer.length < frameLength) {
+      throw new TypeError(`Packet missing payload: frame has length ${frameLength}.`);
     }
 
-    if (suffixLocation !== buffer.length - 4) {
-      leftover = buffer.slice(suffixLocation + 4);
-      buffer = buffer.slice(0, suffixLocation + 4);
+    if (buffer.length > frameLength) {
+      leftover = buffer.slice(frameLength);
+      buffer = buffer.slice(0, frameLength);
     }
 
     // Check for suffix
diff --git a/test/parser.js b/test/parser.js
index 44dad1b..26bfcbe 100644
--- a/test/parser.js
+++ b/test/parser.js
@@ -209,3 +209,24 @@ test('decode message with two packets 2', t => {
   t.deepEqual(parsed.payload, payload);
   t.is(parsed.commandByte, 10);
 });
+
+for (const version of ['3.1', '3.3', '3.4', '3.5']) {
+  for (const sequenceN of [0x0000AA55, 0x00009966]) {
+    test(`decode two packets with protocol ${version} and sequence number holding suffix bytes 0x${sequenceN.toString(16)}`, t => {
+      const payload = {devId: '002004265ccf7fb1b659', dps: {1: true, 2: 0}};
+
+      const parser = new MessageParser({key: 'bbe88b3f4106d354', version});
+      const baseline = parser.parse(parser.encode({data: payload, commandByte: CommandType.DP_QUERY, sequenceN: 1}))[0];
+      const encoded = parser.encode({data: payload, commandByte: CommandType.DP_QUERY, sequenceN});
+
+      const parsed = parser.parse(Buffer.concat([encoded, encoded]));
+
+      t.is(parsed.length, 2);
+      for (const packet of parsed) {
+        t.is(packet.sequenceN, sequenceN);
+        t.is(packet.commandByte, CommandType.DP_QUERY);
+        t.deepEqual(packet.payload, baseline.payload);
+      }
+    });
+  }
+}