diff --git a/internal/block/block.go b/internal/block/block.go
index 78f5c9e4..df835777 100644
--- a/internal/block/block.go
+++ b/internal/block/block.go
@@ -9,5 +9,6 @@ type Block struct {
 // Extrinsic represents the block extrinsic data
 type Extrinsic struct {
 	ET []*TicketProof
+	EP *PreimageExtrinsic
 	ED *DisputeExtrinsic
 }
diff --git a/internal/block/preimage.go b/internal/block/preimage.go
new file mode 100644
index 00000000..db246d5c
--- /dev/null
+++ b/internal/block/preimage.go
@@ -0,0 +1,9 @@
+package block
+
+// PreimageItem represents a single preimage item in the extrinsic
+type Preimage struct {
+    ServiceIndex uint32
+    Data         []byte
+}
+
+type PreimageExtrinsic []Preimage