diff --git a/unsloth_zoo/compiler.py b/unsloth_zoo/compiler.py
index 664cc741f..98c2a701b 100644
--- a/unsloth_zoo/compiler.py
+++ b/unsloth_zoo/compiler.py
@@ -2395,6 +2395,8 @@ def patch_lora_forwards(torch_compile_options):
             # When autocast is disabled and base_layer has float32 weights,
             # cast x to match the weight dtype to prevent dtype mismatch.
             # For 8-bit layers, the base_layer call was already replaced above.
+            # For 4-bit layers, weight.dtype is uint8 (packed quantized bytes),
+            # so we must skip the cast to avoid corrupting input values.
             _base_layer_call = "result = self.base_layer(x, *args, **kwargs)"
             _m = re.search(r'^( *)' + re.escape(_base_layer_call), source, re.MULTILINE)
             if _m:
@@ -2403,6 +2405,7 @@ def patch_lora_forwards(torch_compile_options):
                     _base_layer_call,
                     f"if not torch.is_autocast_enabled() and hasattr(self.base_layer, 'weight') "
                     f"and self.base_layer.weight is not None "
+                    f"and not hasattr(self.base_layer.weight, 'quant_state') "
                     f"and x.dtype != self.base_layer.weight.dtype:\n"
                     f"{_ind}    x = x.to(self.base_layer.weight.dtype)\n"
                     f"{_ind}{_base_layer_call}",