@@ -475,7 +475,7 @@ impl AmlValue {
 }
 }
 
-pub fn write_buffer_field(&mut self, value: AmlValue, _context: &mut AmlContext) -> Result<(), AmlError> {
+pub fn write_buffer_field(&mut self, value: AmlValue, context: &mut AmlContext) -> Result<(), AmlError> {
 use bitvec::view::BitView;
 
 if let AmlValue::BufferField { buffer_data, offset, length } = self {
@@ -519,6 +519,30 @@ impl AmlValue {
 bitslice[(offset + bits_to_copy)..(offset + length)].fill(false);
 Ok(())
 }
+AmlValue::Field {
+region: _region,
+flags: _flags,
+offset: _field_offset,
+length: _field_length,
+} => {
+/*
+* When a `Field` (FieldUnit) is written into a `BufferField`, the field is read and
+* interpreted as an `Integer`, then written using the same rules as Integer writes.
+* This is permitted by ACPI 19.3.5 (Implicit Data Type Conversion), which allows a
+* FieldUnit to be converted to Integer when used as a source operand.
+*/
+let int_value = value.read_field(context)?.as_integer(context)?;
+
+// Write val into the buffer field as an Integer
+let bits_to_copy = cmp::min(length, 64);
+
+bitslice[offset..(offset + bits_to_copy)]
+.copy_from_bitslice(&int_value.to_le_bytes().view_bits()[..bits_to_copy]);
+
+bitslice[(offset + bits_to_copy)..(offset + length)].fill(false);
+
+Ok(())
+}
 _ => Err(AmlError::TypeCannotBeWrittenToBufferField(value.type_of())),
 }
 } else {