diff --git a/Anoma/Builtin/System.juvix b/Anoma/Builtin/System.juvix
index 97a0f6a..a30c813 100644
--- a/Anoma/Builtin/System.juvix
+++ b/Anoma/Builtin/System.juvix
@@ -78,8 +78,9 @@ syntax alias PRNG := PseudoRandomNumberGenerator;
 --- Creates and initializes a pure PRNG with a seed.
 --- @param The seed.
 --- @return The initialized PRNG.
-builtin anoma-random-generator-init
-axiom pseudoRandomNumberGeneratorInit : Nat -> PRNG;
+-- TODO Conversion should be handled on the base layer.
+-- builtin anoma-random-generator-init
+axiom pseudoRandomNumberGeneratorInit : ByteArray -> PRNG;
 
 --- Returns two distinct PRNGs.
 --- @param The generator to split.
diff --git a/Anoma/Resource/Types.juvix b/Anoma/Resource/Types.juvix
index 4bb085f..5e839f6 100644
--- a/Anoma/Resource/Types.juvix
+++ b/Anoma/Resource/Types.juvix
@@ -3,6 +3,7 @@ module Anoma.Resource.Types;
 import Stdlib.Prelude open;
 import Stdlib.Trait.Ord.Eq open using {fromOrdToEq};
 import Anoma.Primitives.FixedSize open;
+import Anoma.Builtin.ByteArray open;
 import Anoma.Utils open;
 
 --- A fixed-size data type encoding the reference to the resource logic function.
@@ -26,11 +27,11 @@ type NullifierKeyCommitment :=
 
 --- A fixed-size data type encoding a number to be used once ensuring that the resource commitment is unique.
 --- NOTE: This should be a number having an at most negligible chance of repeating is sufficient, e.g., a pseudo-random number.
-type Nonce := mkNonce@{unNonce : MISSING_DEFINITION};
+type Nonce := mkNonce@{unNonce : ByteArray};
 
 --- A fixed-size data type encoding a randomness seed.
 --- NOTE: This seed provides pseudo randomness and cannot be expected to provide true randomness.
-type RandSeed := mkRandSeed@{unRandSeed : MISSING_DEFINITION};
+type RandSeed := mkRandSeed@{unRandSeed : ByteArray};
 
 --- The resource label type.
 type Label := mkLabel@{unLabel : MISSING_DEFINITION};
diff --git a/juvix.lock.yaml b/juvix.lock.yaml
index d721670..e5a94fb 100644
--- a/juvix.lock.yaml
+++ b/juvix.lock.yaml
@@ -2,7 +2,7 @@
 # Do not edit this file manually.
 
 version: 2
-checksum: aee7ca6999521d60319bcb414911575aab7ff59e369c9c4677da9563a6299942
+checksum: 2b4ceed787050a25e74294448dc1bcdd9683916bc5bed83bbcbf6e652897308d
 dependencies:
 - git:
     name: anoma_juvix-stdlib