diff --git a/dub.sdl b/dub.sdl
index d956472..c3201b0 100644
--- a/dub.sdl
+++ b/dub.sdl
@@ -7,17 +7,23 @@ dependency "commandr" version="~>1.1.0"
 dependency "colored" version="~>0.0.33"
 targetType "executable"
 sourcePaths
+
 configuration "clox" {
+	buildOptions "betterC"
+	/* debugVersions "memTrace" */
 	debugVersions "traceExec"
+	/* debugVersions "printCode" */
+	dflags "-checkaction=C"
 	libs "libbacktrace"
-	debugVersions "printCode"
 	targetType "executable"
-	sourcePaths "src/clox" "src/common"
+	sourcePaths "src/clox"
 	buildRequirements "requireBoundsCheck" "requireContracts"
 }
+
 configuration "jlox" {
 	targetType "executable"
 	sourcePaths "src/jlox" "src/common"
 	versions "LoxConcatNonStrings" "LoxExtraNativeFuncs" "LoxPrintMultiple"
 	buildRequirements "requireBoundsCheck" "requireContracts"
 }
+
diff --git a/src/clox/chunk.d b/src/clox/chunk.d
index d473e93..0a2a417 100644
--- a/src/clox/chunk.d
+++ b/src/clox/chunk.d
@@ -1,5 +1,7 @@
 module clox.chunk;
 
+import std.algorithm.searching;
+
 import clox.memory;
 import clox.value;
 
@@ -13,6 +15,11 @@ enum OpCode : ubyte{
 	@(OpColour("255", "200", "100")) True,
 	@(OpColour("255", "200", "100")) False,
 
+	@(OpColour("000", "200", "100")) Pop,
+	@(OpColour("000", "200", "150")) GetGlobal,
+	@(OpColour("000", "200", "150")) DefineGlobal,
+	@(OpColour("000", "200", "150")) SetGlobal,
+
 	@(OpColour("255", "100", "100")) Equal,
 	@(OpColour("255", "100", "100")) Greater,
 	@(OpColour("255", "100", "100")) Less,
@@ -27,6 +34,7 @@ enum OpCode : ubyte{
 
 	@(OpColour("200", "100", "100")) Not,
 	@(OpColour("100", "100", "200")) Negate,
+	@(OpColour("000", "200", "100")) Print,
 	@(OpColour("000", "200", "100")) Return,
 }
 
@@ -55,8 +63,12 @@ struct Chunk{
 		count++;
 	}
 	int addConstant(Value value){
-		 constants.write(value);
-		 return constants.count - 1;
+		int index = cast(int)constants.values[0 .. constants.count].countUntil(value);
+		if(index >= 0)
+			return index;
+		assert(constants.count <= ubyte.max);
+		constants.write(value);
+		return constants.count - 1;
 	}
 	void free(){
 		FREE_ARRAY!ubyte(code, capacity);
diff --git a/src/clox/compiler.d b/src/clox/compiler.d
index 8edc60b..7a4e3ee 100644
--- a/src/clox/compiler.d
+++ b/src/clox/compiler.d
@@ -21,8 +21,9 @@ struct Compiler{
 		compilingChunk = chunk;
 
 		parser.advance();
-		parser.expression();
-		parser.consume(Token.Type.EOF, "Expect end of expression.");
+		while(!parser.match(Token.Type.EOF)){
+			parser.declaration();
+		}
 		end();
 		return !parser.hadError;
 	}
diff --git a/src/clox/dbg.d b/src/clox/dbg.d
index 19d4d27..4d469dd 100644
--- a/src/clox/dbg.d
+++ b/src/clox/dbg.d
@@ -10,15 +10,16 @@ import clox.util;
 
 private int simpleInstruction(alias OpCode op)(const char* name, int offset){
 	enum c = getUDAs!(op, OpColour)[0];
-	printf(colour!("%s\n", c.r, c.g, c.b).ptr, name);
+	printf(colour!("%-27s         ", c.r, c.g, c.b).ptr, name);
 	return offset + 1;
 }
 private int constantInstruction(alias OpCode op)(const char* name, Chunk* chunk, int offset){
 	enum c = getUDAs!(op, OpColour)[0];
 	ubyte constant = chunk.code[offset + 1];
-	printf(ctEval!(colour!("%-16s", c.r, c.g, c.b) ~ " %4d '").ptr, name, constant);
-	chunk.constants.values[constant].print();
-	printf("'\n");
+	printf(ctEval!(colour!("%-14s", c.r, c.g, c.b) ~ colour!(" %4d ", Colour.Black)).ptr, name, constant);
+	int pl = chunk.constants.values[constant].print();
+	foreach(i; 0 .. 16-pl)
+		printf(" ");
 	return offset + 2;
 }
 
@@ -26,11 +27,12 @@ void disassembleChunk(Chunk* chunk, const char* name = "chunk"){
 	printf("  ==  %s  ==\n", name);
 	for(int offset = 0; offset < chunk.count;){
 		offset = disassembleInstruction(chunk, offset);
+		printf("\n");
 	}
 }
 
 int disassembleInstruction(Chunk* chunk, int offset){
-	printf("%04d ", offset);
+	printf("%5d ", offset);
 	if(offset > 0 && chunk.lines[offset] == chunk.lines[offset - 1]){
 		printf(colour!("   | ", Colour.Black).ptr);
 	} else {
@@ -39,14 +41,14 @@ int disassembleInstruction(Chunk* chunk, int offset){
 	ubyte instruction = chunk.code[offset];
 	switch(instruction){
 		static foreach(e; EnumMembers!OpCode){
-			static if(e == OpCode.Constant){
-				case OpCode.Constant: return constantInstruction!(OpCode.Constant)("OP_CONSTANT", chunk, offset);
+			static if(e == OpCode.Constant || e == OpCode.DefineGlobal || e == OpCode.GetGlobal){
+				case e: return constantInstruction!(e)(e.stringof, chunk, offset);
 			} else {
 				case e:
 					return simpleInstruction!e(e.stringof, offset);
 			}
 		}
-		default: printf("Unknown opcode %d\n", instruction);
+		default: printf("Unknown opcode %d", instruction);
 			return offset + 1;
 	}
 }
diff --git a/src/clox/obj.d b/src/clox/obj.d
index 40f211a..a6f7c09 100644
--- a/src/clox/obj.d
+++ b/src/clox/obj.d
@@ -22,9 +22,9 @@ struct Obj{
 		static if(type == Type.None) return &this;
 	}
 
-	void print() const{
+	int print() const{
 		final switch(type){
-			case Type.String: printf(`"%s"`, asString.chars.ptr); break;
+			case Type.String: return printf(`"%s"`, asString.chars.ptr); break;
 			case Type.None: assert(0);
 		}
 	}
diff --git a/src/clox/parser.d b/src/clox/parser.d
index cb943c6..48f1bb9 100644
--- a/src/clox/parser.d
+++ b/src/clox/parser.d
@@ -8,6 +8,8 @@ import clox.compiler;
 import clox.chunk;
 import clox.parserules;
 import clox.util;
+import clox.object;
+import clox.value;
 
 struct Parser{
 	Compiler* compiler;
@@ -33,10 +35,72 @@ struct Parser{
 		}
 		errorAtCurrent(message);
 	}
+	bool check(Token.Type type) => current.type == type;
+	bool match(Token.Type type){
+		if(!check(type))
+			return false;
+		advance();
+		return true;
+	}
 
 	void expression(){
 		parsePrecedence(Precedence.Assignment);
 	}
+	void expressionStatement(){
+		expression();
+		consume(Token.Type.Semicolon, "Expect ';' after expression.");
+		compiler.emitter.emit(OpCode.Pop);
+	}
+	void varDeclaration(){
+		ubyte global = parseVariable("Expect variable name.");
+		if(match(Token.Type.Equal))
+			expression();
+		else
+			compiler.emitter.emit(OpCode.Nil);
+		consume(Token.Type.Semicolon, "Expect ';' after variable declaration.");
+		defineVariable(global);
+	}
+	void declaration(){
+		if(match(Token.Type.Var))
+			varDeclaration();
+		else
+			statement();
+		if(compiler.parser.panicMode)
+			synchronize();
+	}
+	void statement(){
+		if(match(Token.Type.Print))
+			printStatement();
+		else
+			expressionStatement();
+	}
+	void printStatement(){
+		expression();
+		consume(Token.Type.Semicolon, "Expect ';' after value.");
+		compiler.emitter.emit(OpCode.Print);
+	}
+
+	void defineVariable(ubyte global){
+		compiler.emitter.emit(OpCode.DefineGlobal, global);
+	}
+	ubyte parseVariable(const char* errorMessage){
+		consume(Token.Type.Identifier, errorMessage);
+		return identifierConstant(&previous);
+	}
+	ubyte identifierConstant(Token* name){
+		Value nameVal = Value.from(Obj.String.copy(name.lexeme));
+		return cast(ubyte)compiler.emitter.makeConstant(nameVal);
+	}
+	void namedVariable(Token name, bool canAssign){
+		ubyte arg = compiler.parser.identifierConstant(&name);
+		if(canAssign && match(Token.Type.Equal)){
+			expression();
+			compiler.emitter.emit(OpCode.SetGlobal, arg);
+		} else {
+			compiler.emitter.emit(OpCode.GetGlobal, arg);
+		}
+	}
+
 	void parsePrecedence(Precedence precedence){
 		advance();
 		ParseFn prefixRule = ParseRule.get(previous.type).prefix;
@@ -44,14 +108,37 @@ struct Parser{
 			error("Expect expression.");
 			return;
 		}
-		prefixRule(compiler);
+		bool canAssign = precedence <= Precedence.Assignment;
+		prefixRule(compiler, canAssign);
 		while(precedence <= ParseRule.get(current.type).precedence){
 			advance();
 			ParseFn infixRule = ParseRule.get(previous.type).infix;
 			infixRule(compiler);
 		}
+		if(canAssign && match(Token.Type.Equal))
+			error("Invalid assignment target.");
 	}
 
+	void synchronize(){
+		panicMode = false;
+		while(current.type != Token.Type.EOF){
+			if(previous.type == Token.Type.Semicolon)
+				return;
+			switch(current.type){
+				case Token.Type.Class:
+				case Token.Type.Fun:
+				case Token.Type.Var:
+				case Token.Type.For:
+				case Token.Type.If:
+				case Token.Type.While:
+				case Token.Type.Print:
+				case Token.Type.Return:
+					return;
+				default: break;
+			}
+			advance();
+		}
+	}
 	void errorAtCurrent(in char* message){
 		errorAt(current, message);
 	}
diff --git a/src/clox/parserules.d b/src/clox/parserules.d
index 9e725c4..55fcaa8 100644
--- a/src/clox/parserules.d
+++ b/src/clox/parserules.d
@@ -8,13 +8,13 @@ import clox.emitter;
 import clox.value;
 import clox.object;
 
-alias ParseFn = void function(Compiler* compiler);
+alias ParseFn = void function(Compiler* compiler, bool canAssign = false);
 
-private void grouping(Compiler* compiler){
+private void grouping(Compiler* compiler, bool _){
 	compiler.parser.expression();
 	compiler.parser.consume(Token.Type.RightParen, "Expect ')' after expression.");
 }
-private void unary(Compiler* compiler){
+private void unary(Compiler* compiler, bool _){
 	Token operator = compiler.parser.previous;
 	compiler.parser.parsePrecedence(Precedence.Unary);
 	compiler.emitter.setLine(operator.line);
@@ -24,7 +24,7 @@ private void unary(Compiler* compiler){
 		default: assert(0);
 	}
 }
-private void binary(Compiler* compiler){
+private void binary(Compiler* compiler, bool _){
 	Token operator = compiler.parser.previous;
 	immutable(ParseRule)* rule = ParseRule.get(operator.type);
 	compiler.parser.parsePrecedence(cast(Precedence)(rule.precedence + 1));
@@ -48,14 +48,14 @@ private void binary(Compiler* compiler){
 	}
 }
 
-private void number(Compiler* compiler){
+private void number(Compiler* compiler, bool _){
 	import core.stdc.stdlib : strtod;
 	Token token = compiler.parser.previous;
 	double value = strtod(token.lexeme.ptr, null);
 	compiler.emitter.setLine(token.line);
 	compiler.emitter.emitConstant(Value.from(value));
 }
-private void literal(Compiler* compiler){
+private void literal(Compiler* compiler, bool _){
 	Token token = compiler.parser.previous;
 	compiler.emitter.setLine(token.line);
 	switch(token.type){
@@ -65,13 +65,16 @@ private void literal(Compiler* compiler){
 		default: assert(0);
 	}
 }
-private void strlit(Compiler* compiler){
+private void strlit(Compiler* compiler, bool _){
 	Token token = compiler.parser.previous;
 	const char[] str = token.lexeme[1 .. $-1];
 	Obj.String* strObj = Obj.String.copy(str);
 	compiler.emitter.setLine(token.line);
 	compiler.emitter.emitConstant(Value.from(strObj));
 }
+private void variable(Compiler* compiler, bool canAssign){
+	compiler.parser.namedVariable(compiler.parser.previous, canAssign);
+}
 
 
 struct ParseRule{
@@ -117,7 +120,7 @@ immutable ParseRule[Token.Type.max+1] rules = [
 	Token.Type.GreaterEqual  : ParseRule(null,      &binary, Precedence.Comparison),
 	Token.Type.Less          : ParseRule(null,      &binary, Precedence.Comparison),
 	Token.Type.LessEqual     : ParseRule(null,      &binary, Precedence.Comparison),
-	Token.Type.Identifier    : ParseRule(null,      null,    Precedence.None),
+	Token.Type.Identifier    : ParseRule(&variable, null,    Precedence.None),
 	Token.Type.String        : ParseRule(&strlit,   null,    Precedence.None),
 	Token.Type.Number        : ParseRule(&number,   null,    Precedence.None),
 	Token.Type.And           : ParseRule(null,      null,    Precedence.None),
diff --git a/src/clox/value.d b/src/clox/value.d
index ff985a5..d0a8e98 100644
--- a/src/clox/value.d
+++ b/src/clox/value.d
@@ -60,12 +60,12 @@ struct Value{
 			case Type.None: assert(0);
 		}
 	}
-	void print() const{
+	int print() const{
 		final switch(type){
-			case Type.Number: printf("%g", asNumber); break;
-			case Type.Bool:   printf(asBoolean ? "true" : "false"); break;
-			case Type.Nil:    printf("nil"); break;
-			case Type.Obj:    asObj.print(); break;
+			case Type.Number: return printf("%g", asNumber);
+			case Type.Bool:   return printf(asBoolean ? "true" : "false");
+			case Type.Nil:    return printf("nil");
+			case Type.Obj:    return asObj.print();
 			case Type.None: assert(0);
 		}
 	}
diff --git a/src/clox/vm.d b/src/clox/vm.d
index 4d4cefa..d77a1fc 100644
--- a/src/clox/vm.d
+++ b/src/clox/vm.d
@@ -3,6 +3,7 @@ module clox.vm;
 import core.stdc.stdio;
 
 import clox.chunk;
+import clox.util;
 import clox.dbg;
 import clox.object;
 import clox.value;
@@ -18,16 +19,19 @@ struct VM{
 	Chunk* chunk;
 	ubyte* ip;
 	Stack!(Value, 256) stack;
+	Table globals;
 	Table strings;
 	Obj* objects;
 	enum InterpretResult{ Ok, CompileError, RuntimeError }
 	void initialise(){
 		stack.reset();
 		strings.initialise();
+		globals.initialise();
 	}
 	void free(){
 		freeObjects();
 		strings.free();
+		globals.free();
 	}
 	InterpretResult interpret(const char* source){
 		Chunk cnk;
@@ -53,7 +57,8 @@ struct VM{
 	InterpretResult run(){
 		ubyte readByte() => *vm.ip++;
 		auto readConstant() => chunk.constants.values[readByte()];
-		Value peek(int distance) => stack.top[-1 - distance];
+		Obj.String* readString() => readConstant().asObj.asString;
+		Value peek(int distance = 0) => stack.top[-1 - distance];
 		bool checkBinaryType(alias type)() => peek(0).isType(type) && peek(1).isType(type);
 		bool checkSameType()() => peek(0).type == peek(1).type;
 		int binaryOp(string op, alias check, string checkMsg, alias pre)(){
@@ -68,14 +73,14 @@ struct VM{
 		}
 		while(true){
 			debug(traceExec){
-				printf("          ");
+				disassembleInstruction(vm.chunk, cast(int)(vm.ip - vm.chunk.code));
+				printf(" ");
 				foreach(slot; stack.live){
-					printf("[ ");
+					printf("");
 					slot.print();
-					printf(" ]");
+					printf(colour!(", ", Colour.Black).ptr);
 				}
 				printf("\n");
-				disassembleInstruction(vm.chunk, cast(int)(vm.ip - vm.chunk.code));
 			}
 			OpCode instruction;
 			opSwitch: final switch(instruction = cast(OpCode)readByte()){
@@ -86,6 +91,30 @@ struct VM{
 				case OpCode.Nil:   stack.push(Value.nil); break;
 				case OpCode.True:  stack.push(Value.from(true)); break;
 				case OpCode.False: stack.push(Value.from(false)); break;
+				case OpCode.Pop:   stack.pop(); break;
+
+				case OpCode.GetGlobal:
+					Obj.String* name = readString();
+					Value value;
+					if(!globals.get(name, value)){
+						runtimeError("Undefined variable '%s'.", name.chars.ptr);
+						return InterpretResult.RuntimeError;
+					}
+					stack.push(value);
+					break;
+				case OpCode.DefineGlobal:
+					Obj.String* name = readString();
+					globals.set(name, peek(0));
+					stack.pop();
+					break;
+				case OpCode.SetGlobal:
+					Obj.String* name = readString();
+					if(globals.set(name, peek(0))){
+						globals.del(name);
+						runtimeError("Undefined variable '%s'.", name.chars.ptr);
+						return InterpretResult.RuntimeError;
+					}
+					break;
 
 				static foreach(k, op; [ OpCode.Equal: "==", OpCode.NotEqual: "!=" ]){
 					case k:
@@ -125,9 +154,11 @@ struct VM{
 					}
 					stack.push(Value.from(-stack.pop().asNumber));
 					break;
-				case OpCode.Return: 
+				case OpCode.Print:
 					stack.pop().print();
 					printf("\n");
+					break;
+				case OpCode.Return:
 					return InterpretResult.Ok;
 			}
 		}