diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8b89896..d43741d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -85,7 +85,8 @@ target_compile_options(lib${PROJECT_NAME} PRIVATE ${warnings})
 # tests
 #
 
-add_executable(${PROJECT_NAME}-bytecode-test src/bytecode/tests.cc)
+add_executable(${PROJECT_NAME}-bytecode-test src/bytecode/tests.cc
+        src/vm/location.hh)
 target_link_libraries(${PROJECT_NAME}-bytecode-test lib${PROJECT_NAME} gtest_main)
 add_test(NAME tyche_bytecode_test COMMAND ${PROJECT_NAME}-bytecode-test)
 
diff --git a/src/vm/code.cc b/src/vm/code.cc
index 450963c..1f2cb81 100644
--- a/src/vm/code.cc
+++ b/src/vm/code.cc
@@ -14,6 +14,41 @@ FunctionId Code::import_bytecode(ByteArray incoming)
     return 0;  // TODO
 }
 
+Operation Code::operation(Location const& location) const
+{
+    Instruction inst = (Instruction) bytecode_.get_code_byte(location.function_id, location.pc);
+    OperandType opet = instruction_operand_type(inst);
+
+    switch (opet) {
+        case OperandType::NoOperand:
+            return {
+                .instruction = inst,
+                .operator_ = 0,
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 1 },
+            };
+        case OperandType::Int8:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int8(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 2 },
+            };
+        case OperandType::Int16:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int16(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 3 },
+            };
+        case OperandType::Int32:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int32(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 5 },
+            };
+    }
+
+    throw std::logic_error("Should not get here");
+}
+
 std::string Code::disassemble() const
 {
     std::string out;
diff --git a/src/vm/code.hh b/src/vm/code.hh
index 2925be3..19084b6 100644
--- a/src/vm/code.hh
+++ b/src/vm/code.hh
@@ -1,17 +1,28 @@
 #ifndef TYCHE_CODE_HH
 #define TYCHE_CODE_HH
 
+#include "instruction.hh"
+#include "location.hh"
 #include "value.hh"
 #include "../bytecode/bytecode.hh"
 
 namespace tyche {
 
+struct Operation
+{
+    Instruction instruction;
+    int32_t     operator_;
+    Location    next_location;
+};
+
 class Code {
 public:
     FunctionId import_bytecode(ByteArray incoming);
 
     [[nodiscard]] std::string disassemble() const;
 
+    [[nodiscard]] Operation operation(Location const& location) const;
+
 private:
     Bytecode bytecode_;
 };
diff --git a/src/vm/instruction.cc b/src/vm/instruction.cc
index 50077a5..d83a8c5 100644
--- a/src/vm/instruction.cc
+++ b/src/vm/instruction.cc
@@ -98,30 +98,48 @@ std::pair<std::string, size_t> debug_instruction(Instruction inst, int oper)
             out = "???";
     }
 
-    if ((uint8_t) inst < 0xa0)
+    OperandType operands = instruction_operand_type(inst);
+
+    if (operands == OperandType::NoOperand)
         return { out, 1 };
 
     out += " " + std::to_string(oper);
-    if ((uint8_t) inst >= 0xe0)
+    if (operands == OperandType::Int32)
         return { out, 5 };
-    else if ((uint8_t) inst >= 0xc0)
+    if (operands == OperandType::Int16)
         return { out, 3 };
-    else
-        return { out, 2 };
+
+    return { out, 2 };
 }
 
 std::pair<std::string, size_t> debug_instruction(Bytecode const& bt, uint32_t function_id, uint32_t addr)
 {
     auto inst = (Instruction) bt.get_code_byte(function_id, addr);
 
-    if ((uint8_t) inst >= 0xe0)
-        return debug_instruction(inst, bt.get_code_int32(function_id, addr + 1));
-    else if ((uint8_t) inst >= 0xc0)
-        return debug_instruction(inst, bt.get_code_int16(function_id, addr + 1));
-    else if ((uint8_t) inst >= 0xa0)
-        return debug_instruction(inst, bt.get_code_int8(function_id, addr + 1));
+    switch (instruction_operand_type(inst)) {
+        case OperandType::NoOperand:
+            return debug_instruction(inst);
+        case OperandType::Int8:
+            return debug_instruction(inst, bt.get_code_int8(function_id, addr + 1));
+        case OperandType::Int16:
+            return debug_instruction(inst, bt.get_code_int16(function_id, addr + 1));
+        case OperandType::Int32:
+            return debug_instruction(inst, bt.get_code_int32(function_id, addr + 1));
+        default:
+    }
 
-    return debug_instruction(inst);
+    return { "???", 1 };
+}
+
+OperandType instruction_operand_type(Instruction inst)
+{
+    if ((uint8_t) inst >= 0xe0)
+        return OperandType::Int32;
+    if ((uint8_t) inst >= 0xc0)
+        return OperandType::Int16;
+    if ((uint8_t) inst >= 0xa0)
+        return OperandType::Int8;
+    return OperandType::NoOperand;
 }
 
 }
\ No newline at end of file
diff --git a/src/vm/instruction.hh b/src/vm/instruction.hh
index 0cb9959..1bbc202 100644
--- a/src/vm/instruction.hh
+++ b/src/vm/instruction.hh
@@ -98,6 +98,9 @@ enum class Instruction : uint8_t {
 std::pair<std::string, size_t> debug_instruction(Instruction inst, int oper=0);
 std::pair<std::string, size_t> debug_instruction(Bytecode const& bt, uint32_t function_id, uint32_t addr);
 
+enum class OperandType { NoOperand, Int8, Int16, Int32 };
+OperandType instruction_operand_type(Instruction instruction);
+
 }
 
 #endif //TYCHE_INSTRUCTION_HH
diff --git a/src/vm/location.hh b/src/vm/location.hh
new file mode 100644
index 0000000..9e67c76
--- /dev/null
+++ b/src/vm/location.hh
@@ -0,0 +1,16 @@
+#ifndef TYCHE_LOCATION_HH
+#define TYCHE_LOCATION_HH
+
+#include <cstdint>
+
+namespace tyche {
+
+struct Location
+{
+    uint32_t function_id;
+    uint32_t pc;
+};
+
+}
+
+#endif //TYCHE_LOCATION_HH
diff --git a/src/vm/stack.hh b/src/vm/stack.hh
index c6b59ac..f42990b 100644
--- a/src/vm/stack.hh
+++ b/src/vm/stack.hh
@@ -21,6 +21,8 @@ public:
     void push_fp();
     void pop_fp();
 
+    [[nodiscard]] size_t fp_level() const { return fps_.size(); }
+
 private:
     std::vector<Value> stack_;
     std::stack<size_t> fps_;
diff --git a/src/vm/vm.cc b/src/vm/vm.cc
index 705f49d..4874fd5 100644
--- a/src/vm/vm.cc
+++ b/src/vm/vm.cc
@@ -27,7 +27,19 @@ void VM::call(size_t n_params)
 
 void VM::run_until_return()
 {
+    size_t level = stack_.fp_level();
 
+    while (stack_.fp_level() >= level)
+        step();
+}
+
+void VM::step()
+{
+    Operation op = code_.operation(loc_.top());
+    switch (op.instruction) {
+        // TODO
+    }
+    loc_.top() = op.next_location;
 }
 
 } // tyche
diff --git a/src/vm/vm.hh b/src/vm/vm.hh
index 852b583..76f49b9 100644
--- a/src/vm/vm.hh
+++ b/src/vm/vm.hh
@@ -2,6 +2,7 @@
 #define TYCHE_VM_HH
 
 #include "code.hh"
+#include "location.hh"
 #include "stack.hh"
 
 namespace tyche {
@@ -13,9 +14,8 @@ public:
     void call(size_t n_params);
 
 private:
-    struct Location { uint32_t function_id; uint32_t pc; };
-
     void run_until_return();
+    void step();
 
     Stack stack_;
     Code code_;