diff --git a/src/main/java/net/md_5/mc/protocol/PacketDefinitions.java b/src/main/java/net/md_5/mc/protocol/PacketDefinitions.java
index 8d1e003d..cecb25bb 100644
--- a/src/main/java/net/md_5/mc/protocol/PacketDefinitions.java
+++ b/src/main/java/net/md_5/mc/protocol/PacketDefinitions.java
@@ -19,7 +19,6 @@ public class PacketDefinitions {
     private static final Instruction BYTE_INT = new ByteHeader(INT);
     private static final Instruction INT_BYTE = new IntHeader(BYTE);
     private static final Instruction INT_3 = new IntHeader(new JumpOpCode(3));
-    private static final Instruction INT_6 = new IntHeader(new JumpOpCode(6));
     private static final Instruction STRING = new ShortHeader(SHORT);
     private static final Instruction ITEM = new Instruction() {
         @Override
@@ -102,6 +101,20 @@ public class PacketDefinitions {
             return "Unsigned Byte Byte";
         }
     };
+    private static final Instruction OPTIONAL_MOTION = new Instruction() {
+        @Override
+        void read(DataInput in) throws IOException {
+            int data = in.readInt();
+            if (data > 0) {
+                skip(in, 6);
+            }
+        }
+
+        @Override
+        public String toString() {
+            return "Optional Motion";
+        }
+    };
 
     static {
         opCodes[0x00] = new Instruction[]{INT};
@@ -127,7 +140,7 @@ public class PacketDefinitions {
         opCodes[0x14] = new Instruction[]{INT, STRING, INT, INT, INT, BYTE, BYTE, SHORT, METADATA};
         opCodes[0x15] = new Instruction[]{INT, SHORT, BYTE, SHORT, INT, INT, INT, BYTE, BYTE, BYTE};
         opCodes[0x16] = new Instruction[]{INT, INT};
-        opCodes[0x17] = new Instruction[]{INT, BYTE, INT, INT, INT, INT_6};
+        opCodes[0x17] = new Instruction[]{INT, BYTE, INT, INT, INT, OPTIONAL_MOTION};
         opCodes[0x18] = new Instruction[]{INT, BYTE, INT, INT, INT, BYTE, BYTE, BYTE, SHORT, SHORT, SHORT, METADATA};
         opCodes[0x19] = new Instruction[]{INT, STRING, INT, INT, INT, INT};
         opCodes[0x1A] = new Instruction[]{INT, INT, INT, INT, SHORT};