diff --git a/src/pymatgen/io/vasp/inputs.py b/src/pymatgen/io/vasp/inputs.py
index 93f2e89bf6b..b210425a224 100644
--- a/src/pymatgen/io/vasp/inputs.py
+++ b/src/pymatgen/io/vasp/inputs.py
@@ -1044,7 +1044,7 @@ def proc_val(key: str, val: str) -> list | bool | float | int | str:
         )
         lower_str_keys = ("ML_MODE",)
         # String keywords to read "as is" (no case transformation, only stripped)
-        as_is_str_keys = ("SYSTEM",)
+        as_is_str_keys = ("SYSTEM", "WANNIER90_WIN")
 
         def smart_int_or_float_bool(str_: str) -> float | int | bool:
             """Determine whether a string represents an integer or a float."""