diff --git a/umbral/cfrags.py b/umbral/cfrags.py
index e078b11..8269cf7 100644
--- a/umbral/cfrags.py
+++ b/umbral/cfrags.py
@@ -26,7 +26,7 @@ from umbral.curvebn import CurveBN
 from umbral.point import Point
 from umbral.signing import Signature
 from umbral.curve import Curve
-from umbral.random_oracles import hash_to_curvebn
+from umbral.random_oracles import hash_to_curvebn, ExtendedKeccak
 
 
 class CorrectnessProof(object):
@@ -201,7 +201,7 @@ class CapsuleFrag(object):
         if self.proof.metadata is not None:
             hash_input.append(self.proof.metadata)
 
-        h = hash_to_curvebn(*hash_input, params=params)
+        h = hash_to_curvebn(*hash_input, params=params, hash_class=ExtendedKeccak)
         ########
 
         precursor = self.point_precursor
diff --git a/umbral/pre.py b/umbral/pre.py
index 5d47296..e74e5bf 100644
--- a/umbral/pre.py
+++ b/umbral/pre.py
@@ -33,7 +33,7 @@ from umbral.point import Point
 from umbral.signing import Signer
 from umbral.curve import Curve
 from umbral.utils import poly_eval, lambda_coeff
-from umbral.random_oracles import kdf, hash_to_curvebn
+from umbral.random_oracles import kdf, hash_to_curvebn, ExtendedKeccak
 
 from constant_sorrow import constants
 
@@ -362,7 +362,7 @@ def prove_cfrag_correctness(cfrag: CapsuleFrag,
     if metadata is not None:
         hash_input.append(metadata)
 
-    h = hash_to_curvebn(*hash_input, params=params)
+    h = hash_to_curvebn(*hash_input, params=params, hash_class=ExtendedKeccak)
     ########
 
     z3 = t + h * rk