diff --git a/crashlink/core.py b/crashlink/core.py
index 3044420..1a03dc0 100644
--- a/crashlink/core.py
+++ b/crashlink/core.py
@@ -14,7 +14,7 @@
 from io import BytesIO
 from typing import Any, BinaryIO, Dict, List, Literal, Optional, Tuple, TypeVar
 
-T = TypeVar("T", bound="VarInt")  # HACK: easier than reimplementing deserialise for each subclass
+T = TypeVar("T", bound="VarInt")  # easier than reimplementing deserialise for each subclass
 
 from .errors import (FailedSerialisation, InvalidOpCode, MalformedBytecode,
                      NoMagic)
@@ -30,7 +30,6 @@
     USE_TQDM = False
 
 
-# TODO: rewrite all ABCs like this to use the PEP 3119 `abc` module
 class Serialisable(ABC):
     """
     Base class for all serialisable objects.
@@ -218,13 +217,14 @@ def serialise(self) -> bytes:
         )
 
 
-class ResolvableVarInt(VarInt):
+class ResolvableVarInt(VarInt, ABC):
     """
     Base class for resolvable VarInts. Call `resolve` to get a direct reference to the object it points to.
     """
 
+    @abstractmethod
     def resolve(self, code: "Bytecode") -> Any:
-        raise NotImplementedError("resolve is not implemented for this class.")
+        pass
 
 
 class fIndex(ResolvableVarInt):
diff --git a/crashlink/disasm.py b/crashlink/disasm.py
index 7da68a8..20da341 100644
--- a/crashlink/disasm.py
+++ b/crashlink/disasm.py
@@ -412,7 +412,7 @@ def from_asm(asm: str) -> List[Opcode]:
         opargs = opcodes[op]
         for name, type in opargs.items():
             new_value = Opcode.TYPE_MAP[type]()
-            new_value.value = literal_eval(args.pop(0))  # FIXME: unsafe?
+            new_value.value = literal_eval(args.pop(0))
             new_opcode.definition[name] = new_value
         ops.append(new_opcode)
     return ops