diff --git a/convex-core/src/main/java/convex/core/cvm/CVMTag.java b/convex-core/src/main/java/convex/core/cvm/CVMTag.java
index b041ece23..038a20f14 100644
--- a/convex-core/src/main/java/convex/core/cvm/CVMTag.java
+++ b/convex-core/src/main/java/convex/core/cvm/CVMTag.java
@@ -77,11 +77,14 @@ public class CVMTag {
     // ==========================================
 	// CVM Ops
 	
-	// General ops with byte flag
+	// General ops with a single byte flag
 	public static final byte OP_CODED = (byte) 0xC0;
 	public static final byte OPCODE_CONSTANT = (byte) 0xB0;
+	public static final byte OPCODE_LOOKUP = (byte) 0xB1;
 	public static final byte OPCODE_LAMBDA = (byte) 0xBF;
-	
+
+	public static final byte OP_LOOKUP = (byte) 0xC1;
+
 	public static final byte OP_DEF = (byte) 0xCD;
 	
 	public static final byte OP_DO = (byte)0xDA; // (do ...)
diff --git a/convex-core/src/main/java/convex/core/cvm/Ops.java b/convex-core/src/main/java/convex/core/cvm/Ops.java
index 2c16f8e68..f3c0ce827 100644
--- a/convex-core/src/main/java/convex/core/cvm/Ops.java
+++ b/convex-core/src/main/java/convex/core/cvm/Ops.java
@@ -3,7 +3,6 @@
 import convex.core.cvm.ops.Constant;
 import convex.core.cvm.ops.Lambda;
 import convex.core.cvm.ops.Let;
-import convex.core.cvm.ops.Lookup;
 import convex.core.cvm.ops.Query;
 import convex.core.cvm.ops.Set;
 import convex.core.cvm.ops.Try;
@@ -22,7 +21,6 @@ public class Ops {
 	public static final byte TRY = 3;
 	public static final byte LET = 4;
 	public static final byte LOOP = 5;
-	public static final byte LOOKUP = 7;
 	public static final byte LAMBDA = 8;
 	public static final byte QUERY = 9;
 	
@@ -52,8 +50,6 @@ public static <T extends ACell> AOp<T> read(byte tag, Blob b, int pos) throws Ba
 			return Constant.read(b,pos);
 		case Ops.TRY:
 			return Try.read(b,pos);
-		case Ops.LOOKUP:
-			return Lookup.read(b,pos);
 		case CVMTag.OPCODE_LAMBDA:
 			return (AOp<T>) Lambda.read(b,pos); 
 		case Ops.LET:
diff --git a/convex-core/src/main/java/convex/core/cvm/ops/Lookup.java b/convex-core/src/main/java/convex/core/cvm/ops/Lookup.java
index 7642990cb..67486aaf0 100644
--- a/convex-core/src/main/java/convex/core/cvm/ops/Lookup.java
+++ b/convex-core/src/main/java/convex/core/cvm/ops/Lookup.java
@@ -3,14 +3,12 @@
 import convex.core.ErrorCodes;
 import convex.core.cvm.AOp;
 import convex.core.cvm.Address;
+import convex.core.cvm.CVMTag;
 import convex.core.cvm.Context;
 import convex.core.cvm.Juice;
-import convex.core.cvm.Ops;
 import convex.core.data.ACell;
 import convex.core.data.Blob;
-import convex.core.data.Cells;
 import convex.core.data.Format;
-import convex.core.data.IRefFunction;
 import convex.core.data.Ref;
 import convex.core.data.Symbol;
 import convex.core.data.util.BlobBuilder;
@@ -28,17 +26,13 @@
  *
  * @param <T> Result type of Op
  */
-public class Lookup<T extends ACell> extends AOp<T> {
-	private final AOp<Address> address;
-	private final Symbol symbol;
-
-	private Lookup(AOp<Address> address,Symbol symbol) {
-		this.address=address;
-		this.symbol = symbol;
+public class Lookup<T extends ACell> extends ACodedOp<T,AOp<Address>,Symbol> {
+	private Lookup(Ref<AOp<Address>> address,Ref<Symbol> symbol) {
+		super (CVMTag.OP_LOOKUP,address,symbol);
 	}
 
 	public static <T extends ACell> Lookup<T> create(AOp<Address> address, Symbol form) {
-		return new Lookup<T>(address,form);
+		return new Lookup<T>(Ref.get(address),form.getRef());
 	}
 	
 	public static <T extends ACell> Lookup<T> create(AOp<Address> address, String name) {
@@ -61,6 +55,7 @@ public static <T extends ACell> Lookup<T> create(String name) {
 	public Context execute(Context context) {
 		Context rctx=context;
 		Address namespaceAddress=null;
+		AOp<Address> address=code.getValue();
 		if (address!=null) {
 			rctx=rctx.execute(address);
 			if (rctx.isExceptional()) return rctx;
@@ -71,30 +66,21 @@ public Context execute(Context context) {
 		
 		// Do a dynamic lookup, with address if specified or address from current context otherwise
 		namespaceAddress=(address==null)?context.getAddress():namespaceAddress;
+		Symbol symbol=value.getValue();
 		return rctx.lookupDynamic(namespaceAddress,symbol).consumeJuice(Juice.LOOKUP_DYNAMIC);
 	}
 
 	@Override
 	public boolean print(BlobBuilder bb, long limit) {
+		AOp<Address> address=code.getValue();
 		if (address!=null) {
 			if (!address.print(bb,limit)) return false;
 			bb.append('/');
 		}
+		Symbol symbol=value.getValue();
 		return symbol.print(bb,limit);
 	}
 
-	@Override
-	public byte opCode() {
-		return Ops.LOOKUP;
-	}
-
-	@Override
-	public int encodeAfterOpcode(byte[] bs, int pos) {
-		pos= symbol.encode(bs, pos);
-		pos= Format.write(bs,pos, address); // might be null
-		return pos;
-	}
-
 	/**
 	 * Reads a Lookup op from a Blob encoding
 	 * @param <T> Type of Lookup value
@@ -104,48 +90,34 @@ public int encodeAfterOpcode(byte[] bs, int pos) {
 	 * @throws BadFormatException In the event of any encoding error
 	 */
 	public static <T extends ACell> Lookup<T> read(Blob b,int pos) throws BadFormatException {
-		int epos=pos+Ops.OP_DATA_OFFSET; // skip tag and opcode to get to data
+		int epos=pos+1; // skip tag to get to data
 		
-		Symbol sym = Format.read(b,epos);
-		if (sym==null) throw new BadFormatException("Lookup symbol cannot be null");
-		epos+=Cells.getEncodingLength(sym);
+		Ref<AOp<Address>> addr=Format.readRef(b, epos);
+		epos+=addr.getEncodingLength();
 		
-		AOp<Address> address = Format.read(b,epos);
-		epos+=Cells.getEncodingLength(address);
+		Ref<Symbol> sym=Format.readRef(b, epos);
+		epos+=sym.getEncodingLength();
 		
-		Lookup<T> result= create(address,sym);
+		Lookup<T> result= new Lookup<T>(addr,sym);
 		result.attachEncoding(b.slice(pos, epos));
 		return result;
 	}
 
-	@Override
-	public int getRefCount() {
-		if (address==null) return 0;
-		return address.getRefCount();
-	}
 
-	@Override
-	public <R extends ACell> Ref<R> getRef(int i) {
-		if (address==null) throw new IndexOutOfBoundsException();
-		return address.getRef(i);
-	}
-
-	@Override
-	public Lookup<T> updateRefs(IRefFunction func) {
-		if (address==null) return this;
-		AOp<Address> newAddress=address.updateRefs(func);
-		if (address==newAddress) return this;
-		return create(newAddress,symbol);
-	}
 
 	@Override
 	public void validateCell() throws InvalidDataException {
-		if (address!=null) address.validateCell();
-		symbol.validateCell();
+		// TODO: any checks?
 	}
 
 	public AOp<Address> getAddress() {
-		return address;
+		return code.getValue();
+	}
+
+	@Override
+	protected AOp<T> rebuild(Ref<AOp<Address>> newCode, Ref<Symbol> newValue) {
+		if ((code==newCode)&&(value==newValue)) return this;
+		return new Lookup<T>(newCode,newValue);
 	}
 
 
diff --git a/convex-core/src/main/java/convex/core/cvm/ops/Set.java b/convex-core/src/main/java/convex/core/cvm/ops/Set.java
index 95f7591d2..704c72416 100644
--- a/convex-core/src/main/java/convex/core/cvm/ops/Set.java
+++ b/convex-core/src/main/java/convex/core/cvm/ops/Set.java
@@ -5,11 +5,9 @@
 import convex.core.cvm.CVMTag;
 import convex.core.cvm.Context;
 import convex.core.cvm.Juice;
-import convex.core.cvm.Ops;
 import convex.core.data.ACell;
 import convex.core.data.AVector;
 import convex.core.data.Blob;
-import convex.core.data.Cells;
 import convex.core.data.Format;
 import convex.core.data.Ref;
 import convex.core.data.prim.CVMLong;
@@ -77,15 +75,15 @@ public Context execute(Context ctx) {
 	 * @throws BadFormatException In the event of any encoding error
 	 */
 	public static <R extends ACell> Set<R> read(Blob b, int pos) throws BadFormatException{
-		int epos=pos+Ops.OP_DATA_OFFSET; // skip tag and opcode to get to data
+		int epos=pos+1; // skip tag to get to data
 		
-		long position = Format.readVLQLong(b,epos);
-		epos+=Format.getVLQLongLength(position);
+		Ref<CVMLong> index=Format.readRef(b, epos);
+		epos+=index.getEncodingLength();
 		
-		AOp<R> op = Format.read(b,epos);
-		epos+=Cells.getEncodingLength(op);
+		Ref<AOp<R>> op=Format.readRef(b, epos);
+		epos+=op.getEncodingLength();
 		
-		Set<R> result= create(position, op);
+		Set<R> result= new Set<R>(index,op);
 		result.attachEncoding(b.slice(pos, epos));
 		return result;
 	}
diff --git a/convex-core/src/main/java/convex/core/data/Format.java b/convex-core/src/main/java/convex/core/data/Format.java
index 1eff53fd1..d3edac441 100644
--- a/convex-core/src/main/java/convex/core/data/Format.java
+++ b/convex-core/src/main/java/convex/core/data/Format.java
@@ -27,6 +27,7 @@
 import convex.core.cvm.ops.Def;
 import convex.core.cvm.ops.Do;
 import convex.core.cvm.ops.Local;
+import convex.core.cvm.ops.Lookup;
 import convex.core.cvm.ops.Special;
 import convex.core.cvm.transactions.Call;
 import convex.core.cvm.transactions.Invoke;
@@ -499,21 +500,26 @@ private static <T extends ACell> T readDataStructure(byte tag, Blob b, int pos)
 	}
 
 	private static ACell readCode(byte tag, Blob b, int pos) throws BadFormatException {
-		
-		if (tag == CVMTag.OP_DEF) {
-			return Def.read(b, pos);
-		}
-		
-		if (tag == CVMTag.OP_CODED) return Ops.read(tag,b, pos); 
-		
-		if (tag == CVMTag.FN_MULTI) {
-			AFn<?> fn = MultiFn.read(b,pos);
-			return fn;
-		}
-
-		if (tag == CVMTag.FN) {
-			AFn<?> fn = Fn.read(b,pos);
-			return fn;
+		try {
+			if (tag == CVMTag.OP_CODED) return Ops.read(tag,b, pos); 
+			
+			if (tag == CVMTag.OP_LOOKUP) return Lookup.read(b,pos);
+			
+			if (tag == CVMTag.OP_DEF) {
+				return Def.read(b, pos);
+			}
+			
+			if (tag == CVMTag.FN_MULTI) {
+				AFn<?> fn = MultiFn.read(b,pos);
+				return fn;
+			}
+	
+			if (tag == CVMTag.FN) {
+				AFn<?> fn = Fn.read(b,pos);
+				return fn;
+			}
+		} catch (Exception e) {
+			// something went wrong, fall through to reading a generic coded value
 		}
 		
 		return CodedValue.read(tag,b,pos);