diff --git a/poseidon2/sponge.nim b/poseidon2/sponge.nim
index e2bdfc8..a4160d2 100644
--- a/poseidon2/sponge.nim
+++ b/poseidon2/sponge.nim
@@ -1,5 +1,6 @@
 import ./types
 import ./permutation
+import ./io
 import constantine/math/io/io_fields
 import constantine/math/arithmetic