diff --git a/example/hello.wren b/example/hello.wren
index e82f6102..79d3cee8 100644
--- a/example/hello.wren
+++ b/example/hello.wren
@@ -1,6 +1,6 @@
-{
-  123
+var a = {
+  var b = 234
+  3
+  b
 }
-var a = 123
-var b = 345
-a
+a.call
diff --git a/src/compiler.c b/src/compiler.c
index c26bfd1f..2bb2d138 100644
--- a/src/compiler.c
+++ b/src/compiler.c
@@ -110,8 +110,15 @@ static void consume(Compiler* compiler, TokenType expected);
 static void advance(Parser* parser);
 
 // Tokens:
+
+// Lex the next token in the source file and store it in parser.current. Omits
+// newlines that aren't meaningful.
 static void readNextToken(Parser* parser);
+
+// Lex the next token and store it in parser.current. Does not do any newline
+// filtering.
 static void readRawToken(Parser* parser);
+
 static void readName(Parser* parser);
 static void readNumber(Parser* parser);
 static void readString(Parser* parser);
diff --git a/src/main.c b/src/main.c
index 5c8b3ebc..54296cc7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -27,9 +27,14 @@ int main(int argc, const char * argv[])
   char* source = readFile(argv[1], &length);
   VM* vm = newVM();
   ObjBlock* block = compile(vm, source, length);
-  Value value = interpret(vm, block);
-  printValue(value);
-  printf("\n");
+
+  if (block)
+  {
+    Value value = interpret(vm, block);
+    printValue(value);
+    printf("\n");
+  }
+
   freeVM(vm);
   free(source);
 
diff --git a/src/vm.c b/src/vm.c
index b7812826..67b84d83 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -4,6 +4,13 @@
 
 #include "vm.h"
 
+#define PRIMITIVE(cls, prim) \
+    { \
+      int symbol = ensureSymbol(&vm->symbols, #prim, strlen(#prim)); \
+      vm->cls##Class->methods[symbol].type = METHOD_PRIMITIVE; \
+      vm->cls##Class->methods[symbol].primitive = primitive_##cls##_##prim; \
+    }
+
 typedef struct
 {
   // Index of the current (really next-to-be-executed) instruction in the
@@ -29,17 +36,26 @@ typedef struct
 static void callBlock(Fiber* fiber, ObjBlock* block, int firstLocal);
 static void push(Fiber* fiber, Value value);
 static Value pop(Fiber* fiber);
-static Value primitiveNumAbs(Value number);
+static Value primitive_num_abs(Value block);
 
 VM* newVM()
 {
   VM* vm = malloc(sizeof(VM));
   initSymbolTable(&vm->symbols);
 
+  vm->blockClass = makeClass();
+
+  // The call method is special: neither a primitive nor a user-defined one.
+  // This is because it mucks with the fiber itself.
+  {
+    int symbol = ensureSymbol(&vm->symbols, "call", strlen("call"));
+    vm->blockClass->methods[symbol].type = METHOD_CALL;
+  }
+
+  vm->classClass = makeClass();
+
   vm->numClass = makeClass();
-  int symbol = ensureSymbol(&vm->symbols, "abs", 3);
-  vm->numClass->methods[symbol].type = METHOD_PRIMITIVE;
-  vm->numClass->methods[symbol].primitive = primitiveNumAbs;
+  PRIMITIVE(num, abs);
 
   return vm;
 }
@@ -198,7 +214,22 @@ Value interpret(VM* vm, ObjBlock* block)
         int symbol = frame->block->bytecode[frame->ip++];
 
         // TODO(bob): Support classes for other object types.
-        ObjClass* classObj = vm->numClass;
+        ObjClass* classObj;
+        switch (receiver->type)
+        {
+          case OBJ_BLOCK:
+            classObj = vm->blockClass;
+            break;
+
+          case OBJ_CLASS:
+            classObj = vm->classClass;
+            break;
+
+          case OBJ_NUM:
+            classObj = vm->numClass;
+            break;
+        }
+
         Method* method = &classObj->methods[symbol];
         switch (method->type)
         {
@@ -208,6 +239,11 @@ Value interpret(VM* vm, ObjBlock* block)
             exit(1);
             break;
 
+          case METHOD_CALL:
+            // TODO(bob): Should pass in correct index for locals.
+            callBlock(&fiber, (ObjBlock*)receiver, fiber.stackSize);
+            break;
+
           case METHOD_PRIMITIVE:
             push(&fiber, method->primitive(receiver));
             break;
@@ -282,7 +318,7 @@ Value pop(Fiber* fiber)
   return fiber->stack[--fiber->stackSize];
 }
 
-Value primitiveNumAbs(Value number)
+Value primitive_num_abs(Value number)
 {
   double value = ((ObjNum*)number)->value;
   if (value < 0) value = -value;
diff --git a/src/vm.h b/src/vm.h
index fd6cd159..ebbc913e 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -46,6 +46,7 @@ typedef Value (*Primitive)(Value receiver);
 typedef enum
 {
   METHOD_NONE,
+  METHOD_CALL,
   METHOD_PRIMITIVE,
   METHOD_BLOCK
 } MethodType;
@@ -105,6 +106,9 @@ typedef struct
 typedef struct
 {
   SymbolTable symbols;
+
+  ObjClass* blockClass;
+  ObjClass* classClass;
   ObjClass* numClass;
 } VM;