diff --git a/riscemu/decoder/__init__.py b/riscemu/decoder/__init__.py
index 3ba852e..e68396a 100644
--- a/riscemu/decoder/__init__.py
+++ b/riscemu/decoder/__init__.py
@@ -1 +1 @@
-from .decoder import decode
\ No newline at end of file
+from .decoder import decode, RISCV_REGS
diff --git a/riscemu/decoder/__main__.py b/riscemu/decoder/__main__.py
index e109c97..98bc146 100644
--- a/riscemu/decoder/__main__.py
+++ b/riscemu/decoder/__main__.py
@@ -6,6 +6,7 @@ if __name__ == '__main__':
     from .decoder import *
     from .formats import *
     from .instruction_table import *
+    from .regs import RISCV_REGS
 
     sess_vars = globals()
     sess_vars.update(locals())
@@ -13,4 +14,4 @@ if __name__ == '__main__':
     readline.set_completer(rlcompleter.Completer(sess_vars).complete)
     readline.set_completer(rlcompleter.Completer(sess_vars).complete)
     readline.parse_and_bind("tab: complete")
-    code.InteractiveConsole(sess_vars).interact(banner="Interaktive decoding session started...", exitmsg="Closing...")
\ No newline at end of file
+    code.InteractiveConsole(sess_vars).interact(banner="Interaktive decoding session started...", exitmsg="Closing...")
diff --git a/riscemu/decoder/decoder.py b/riscemu/decoder/decoder.py
index f0601e8..5b198ad 100644
--- a/riscemu/decoder/decoder.py
+++ b/riscemu/decoder/decoder.py
@@ -8,11 +8,11 @@ def print_ins(ins: int):
         f"0b{ins >> 25 :07b}_{(ins >> 20) & 0b11111:05b}_{(ins >> 15) & 0b11111:03b}_{(ins >> 12) & 0b111:03b}_{(ins >> 7) & 0b11111:05b}_{ins & 0b1111111:07b}");
 
 
-STATIC_INSN: Dict[int, Tuple[str, List[Union[str, int]], int]] = {
+STATIC_INSN: Dict[int, Tuple[str, List[int], int]] = {
     0x00000013: ("nop", [], 0x00000013),
     0x00008067: ("ret", [], 0x00008067),
-    0xfe010113: ("addi", ["sp", "sp", -32], 0xfe010113),
-    0x02010113: ("addi", ["sp", "sp", 32], 0x02010113),
+    0xfe010113: ("addi", [2, 2, -32], 0xfe010113),
+    0x02010113: ("addi", [2, 2, 32], 0x02010113),
     0x00100073: ("ebreak", [], 0x00100073),
     0x00000073: ("ecall", [], 0x00000073),
     0x30200073: ("mret", [], 0x30200073),
@@ -72,7 +72,7 @@ def name_from_insn(ins: int):
     raise RuntimeError(f"Invalid instruction: {ins:x}")
 
 
-def decode(ins: bytearray) -> Tuple[str, List[Union[str, int]], int]:
+def decode(ins: bytearray) -> Tuple[str, List[int], int]:
     insn = int_from_ins(ins)
 
     if insn & 3 != 3:
diff --git a/riscemu/decoder/formats.py b/riscemu/decoder/formats.py
index ccca92f..0b67d6a 100644
--- a/riscemu/decoder/formats.py
+++ b/riscemu/decoder/formats.py
@@ -69,37 +69,37 @@ def sign_extend(num, bits):
     return (num & (sign_mask - 1)) - (num & sign_mask)
 
 
-def decode_i(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rd(ins)], RISCV_REGS[rs1(ins)], imm_i(ins)]
+def decode_i(ins: int) -> List[int]:
+    return [rd(ins), rs1(ins), imm_i(ins)]
 
 
-def decode_b(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rs1(ins)], RISCV_REGS[rs2(ins)], imm_b(ins)]
+def decode_b(ins: int) -> List[int]:
+    return [rs1(ins), rs2(ins), imm_b(ins)]
 
 
-def decode_u(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rd(ins)], imm_u(ins)]
+def decode_u(ins: int) -> List[int]:
+    return [rd(ins), imm_u(ins)]
 
 
-def decode_r(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rd(ins)], RISCV_REGS[rs1(ins)], RISCV_REGS[rs2(ins)]]
+def decode_r(ins: int) -> List[int]:
+    return [rd(ins), rs1(ins), rs2(ins)]
 
 
-def decode_s(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rs1(ins)], RISCV_REGS[rs2(ins)], imm_s(ins)]
+def decode_s(ins: int) -> List[int]:
+    return [rs2(ins), rs1(ins), imm_s(ins)]
 
 
-def decode_j(ins: int) -> List[Union[str, int]]:
-    return [RISCV_REGS[rd(ins)], imm_j(ins)]
+def decode_j(ins: int) -> List[int]:
+    return [rd(ins), imm_j(ins)]
 
 
-def decode_i_shamt(ins: int) -> List[Union[str, int]]:
+def decode_i_shamt(ins: int) -> List[int]:
     if funct3(ins) in (1, 5):
-        return [RISCV_REGS[rd(ins)], RISCV_REGS[rs1(ins)], rs2(ins)]
+        return [rd(ins), rs1(ins), rs2(ins)]
     return decode_i(ins)
 
 
-INSTRUCTION_ARGS_DECODER: Dict[int, Callable[[int], List[Union[str, int]]]] = {
+INSTRUCTION_ARGS_DECODER: Dict[int, Callable[[int], List[int]]] = {
     0x00: decode_i,
     0x04: decode_i_shamt,
     0x05: decode_u,
diff --git a/riscemu/priv/ElfLoader.py b/riscemu/priv/ElfLoader.py
index 09ac73d..cf58bea 100644
--- a/riscemu/priv/ElfLoader.py
+++ b/riscemu/priv/ElfLoader.py
@@ -7,7 +7,7 @@ from elftools.elf.sections import Section, SymbolTableSection
 from .Exceptions import *
 from ..Exceptions import RiscemuBaseException
 from ..Executable import MemoryFlags, LoadedMemorySection
-from ..decoder import decode
+from ..decoder import decode, RISCV_REGS
 from ..helpers import FMT_PARSE, FMT_NONE, FMT_GREEN, FMT_BOLD
 
 FMT_ELF = FMT_GREEN + FMT_BOLD
@@ -96,17 +96,17 @@ class InvalidElfException(RiscemuBaseException):
 @dataclass(frozen=True)
 class ElfInstruction:
     name: str
-    args: List[Union[int, str]]
+    args: List[int]
     encoded: int
 
-    def get_imm(self, num: int):
-        return self.args[-1]
+    def get_imm(self, num: int) -> int:
+        return self.args[num]
 
-    def get_imm_reg(self, num: int):
+    def get_imm_reg(self, num: int) -> Tuple[int, int]:
         return self.args[-1], self.args[-2]
 
-    def get_reg(self, num: int):
-        return self.args[num]
+    def get_reg(self, num: int) -> str:
+        return RISCV_REGS[self.args[num]]
 
     def __repr__(self):
         if self.name in ('sw', 'sh', 'sb', 'lb', 'lh', 'lb', 'lbu', 'lhu'):