diff --git a/src/vm/tests.cc b/src/vm/tests.cc
index 0f92135..47b29fe 100644
--- a/src/vm/tests.cc
+++ b/src/vm/tests.cc
@@ -5,6 +5,7 @@
 #include "../bytecode/bytecode.hh"
 #include "code.hh"
 #include "stack.hh"
+#include "vm.hh"
 
 using namespace tyche;
 
@@ -68,6 +69,27 @@ TEST(Stack, FramePointer)
     ASSERT_EQ(stack.at(-2).as_integer(), 10);
 }
 
+TEST(VM, BasicCode)
+{
+    // code (2+3)
+    BytecodePrototype bp;
+    bp.functions.emplace_back(0, 0);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::PushInt8);
+    bp.functions.at(0).code.append_int8(2);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::PushInt8);
+    bp.functions.at(0).code.append_int8(3);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::Sum);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::Return);
+    ByteArray ba = Bytecode::generate(bp);
+
+    VM vm;
+    vm.load_bytecode(std::move(ba));
+    vm.call(0);
+
+    int32_t result = vm.to_integer(-1);
+    ASSERT_EQ(result, 5);
+}
+
 int main(int argc, char** argv)
 {
     testing::InitGoogleTest(&argc, argv);
diff --git a/src/vm/vm.cc b/src/vm/vm.cc
index 4874fd5..18c4ed9 100644
--- a/src/vm/vm.cc
+++ b/src/vm/vm.cc
@@ -25,6 +25,18 @@ void VM::call(size_t n_params)
     loc_.pop();
 }
 
+int32_t VM::to_integer(int index) const
+{
+    Value i = stack_.at(index);
+    assert_type(i, Type::Integer);
+    return i.as_integer();
+}
+
+void VM::push_integer(int32_t value)
+{
+    stack_.push(Value::CreateInteger(value));
+}
+
 void VM::run_until_return()
 {
     size_t level = stack_.fp_level();
@@ -37,9 +49,21 @@ void VM::step()
 {
     Operation op = code_.operation(loc_.top());
     switch (op.instruction) {
-        // TODO
+        case Instruction::PushInt8:
+        case Instruction::PushInt16:
+        case Instruction::PushInt32:
+            push_integer(op.operator_);
+            break;
+        default:
+            throw VMInvalidOpcode((uint8_t) op.instruction);
     }
     loc_.top() = op.next_location;
 }
 
+void VM::assert_type(Value const& val, Type type)
+{
+    if (val.type() != type)
+        throw VMTypeError(type, val.type());
+}
+
 } // tyche
diff --git a/src/vm/vm.hh b/src/vm/vm.hh
index 76f49b9..ef8554b 100644
--- a/src/vm/vm.hh
+++ b/src/vm/vm.hh
@@ -13,10 +13,16 @@ public:
 
     void call(size_t n_params);
 
+    [[nodiscard]] int32_t to_integer(int index) const;
+
+    void push_integer(int32_t value);
+
 private:
     void run_until_return();
     void step();
 
+    static void assert_type(Value const& val, Type type);
+
     Stack stack_;
     Code code_;
     std::stack<Location> loc_;
diff --git a/src/vm/vm_exceptions.hh b/src/vm/vm_exceptions.hh
index 7bebf3c..d20eac5 100644
--- a/src/vm/vm_exceptions.hh
+++ b/src/vm/vm_exceptions.hh
@@ -30,6 +30,11 @@ public:
     explicit VMTypeError(Type expected, Type found) : VMRuntimeError("Type error") {}  // TODO - print types
 };
 
+class VMInvalidOpcode : public VMRuntimeError
+{
+public:
+    explicit VMInvalidOpcode(uint8_t opcode) : VMRuntimeError("Invalid opcode " + std::to_string(opcode)) {}
+};
 
 }