diff --git a/src/imagination/pco/pco_common.h.py b/src/imagination/pco/pco_common.h.py
index 045eea93890..dce8955c420 100644
--- a/src/imagination/pco/pco_common.h.py
+++ b/src/imagination/pco/pco_common.h.py
@@ -51,7 +51,7 @@ static bool ${enum.name}_valid(uint64_t val)
 % for bit_set in bit_sets.values():
 enum ${bit_set.name}_variant {
    ${bit_set.name.upper()}_NONE,
-   % for variant in bit_set.variants:
+   % for variant, *_ in bit_set.variants:
    ${variant},
    % endfor
 };
diff --git a/src/imagination/pco/pco_isa.h.py b/src/imagination/pco/pco_isa.h.py
index b0575c53baa..1b120a58191 100644
--- a/src/imagination/pco/pco_isa.h.py
+++ b/src/imagination/pco/pco_isa.h.py
@@ -32,6 +32,19 @@ enum ${bit_set.name}_field {
    % endfor
 };
 
+static unsigned ${bit_set.name}_bytes(enum ${bit_set.name}_variant variant)
+{
+   switch (variant) {
+   case ${bit_set.name.upper()}_NONE: return 0;
+   % for variant, num_bytes in bit_set.variants:
+   case ${variant}: return ${num_bytes};
+   % endfor
+   default: break;
+   }
+
+   unreachable();
+}
+
 static unsigned ${bit_set.name}_encode_field(uint8_t *bin, enum ${bit_set.name}_field field, uint64_t val)
 {
    uint64_t enc_val;
diff --git a/src/imagination/pco/pco_pygen_common.py b/src/imagination/pco/pco_pygen_common.py
index 9fd2621362a..4a8bd825cf2 100644
--- a/src/imagination/pco/pco_pygen_common.py
+++ b/src/imagination/pco/pco_pygen_common.py
@@ -344,8 +344,9 @@ def bit_struct(name, bit_set, field_mappings, data=None):
    assert (total_bits % 8) == 0, f'Bit struct "{name}" has a non-byte-aligned number of bits ({total_bits}).'
 
    _name = f'{bit_set.name}_{name}'
-   bs = BitStruct(_name, struct_fields, encode_fields, total_bits // 8, data)
+   total_bytes = total_bits // 8
+   bs = BitStruct(_name, struct_fields, encode_fields, total_bytes, data)
    bit_set.bit_structs[name] = bs
-   bit_set.variants.append(f'{bit_set.name}_{name}'.upper())
+   bit_set.variants.append((f'{bit_set.name}_{name}'.upper(), total_bytes))
 
    return bs