diff --git a/beacon_node/beacon_chain/test_harness/src/test_case.rs b/beacon_node/beacon_chain/test_harness/src/test_case.rs
index a18b4688b..b6b1ea5cc 100644
--- a/beacon_node/beacon_chain/test_harness/src/test_case.rs
+++ b/beacon_node/beacon_chain/test_harness/src/test_case.rs
@@ -9,9 +9,7 @@ use ssz::SignedRoot;
 use std::path::Path;
 use types::*;
 
-use types::{
-    attester_slashing::AttesterSlashingBuilder, proposer_slashing::ProposerSlashingBuilder,
-};
+use types::test_utils::{TestingAttesterSlashingBuilder, TestingProposerSlashingBuilder};
 use yaml_rust::Yaml;
 
 mod config;
@@ -331,7 +329,7 @@ fn build_double_vote_attester_slashing(
             .expect("Unable to sign AttesterSlashing")
     };
 
-    AttesterSlashingBuilder::double_vote(validator_indices, signer)
+    TestingAttesterSlashingBuilder::double_vote(validator_indices, signer)
 }
 
 /// Builds an `ProposerSlashing` for some `validator_index`.
@@ -344,5 +342,5 @@ fn build_proposer_slashing(harness: &BeaconChainHarness, validator_index: u64) -
             .expect("Unable to sign AttesterSlashing")
     };
 
-    ProposerSlashingBuilder::double_vote(validator_index, signer, &harness.spec)
+    TestingProposerSlashingBuilder::double_vote(validator_index, signer, &harness.spec)
 }
diff --git a/eth2/types/src/attester_slashing.rs b/eth2/types/src/attester_slashing.rs
index 1cb671960..7a0752b6a 100644
--- a/eth2/types/src/attester_slashing.rs
+++ b/eth2/types/src/attester_slashing.rs
@@ -4,10 +4,6 @@ use serde_derive::Serialize;
 use ssz_derive::{Decode, Encode, TreeHash};
 use test_random_derive::TestRandom;
 
-mod builder;
-
-pub use builder::AttesterSlashingBuilder;
-
 /// Two conflicting attestations.
 ///
 /// Spec v0.4.0
diff --git a/eth2/types/src/proposer_slashing.rs b/eth2/types/src/proposer_slashing.rs
index f86e7f3a8..394c55a01 100644
--- a/eth2/types/src/proposer_slashing.rs
+++ b/eth2/types/src/proposer_slashing.rs
@@ -5,10 +5,6 @@ use serde_derive::Serialize;
 use ssz_derive::{Decode, Encode, TreeHash};
 use test_random_derive::TestRandom;
 
-mod builder;
-
-pub use builder::ProposerSlashingBuilder;
-
 /// Two conflicting proposals from the same proposer (validator).
 ///
 /// Spec v0.4.0
diff --git a/eth2/types/src/test_utils/mod.rs b/eth2/types/src/test_utils/mod.rs
index 26d340e7d..6fdbe53ad 100644
--- a/eth2/types/src/test_utils/mod.rs
+++ b/eth2/types/src/test_utils/mod.rs
@@ -2,9 +2,11 @@ mod generate_deterministic_keypairs;
 mod keypairs_file;
 mod test_random;
 mod testing_attestation_builder;
+mod testing_attester_slashing_builder;
 mod testing_beacon_block_builder;
 mod testing_beacon_state_builder;
 mod testing_deposit_builder;
+mod testing_proposer_slashing_builder;
 mod testing_transfer_builder;
 mod testing_voluntary_exit_builder;
 
@@ -13,8 +15,10 @@ pub use keypairs_file::KeypairsFile;
 pub use rand::{prng::XorShiftRng, SeedableRng};
 pub use test_random::TestRandom;
 pub use testing_attestation_builder::TestingAttestationBuilder;
+pub use testing_attester_slashing_builder::TestingAttesterSlashingBuilder;
 pub use testing_beacon_block_builder::TestingBeaconBlockBuilder;
 pub use testing_beacon_state_builder::{keypairs_path, TestingBeaconStateBuilder};
 pub use testing_deposit_builder::TestingDepositBuilder;
+pub use testing_proposer_slashing_builder::TestingProposerSlashingBuilder;
 pub use testing_transfer_builder::TestingTransferBuilder;
 pub use testing_voluntary_exit_builder::TestingVoluntaryExitBuilder;
diff --git a/eth2/types/src/attester_slashing/builder.rs b/eth2/types/src/test_utils/testing_attester_slashing_builder.rs
similarity index 97%
rename from eth2/types/src/attester_slashing/builder.rs
rename to eth2/types/src/test_utils/testing_attester_slashing_builder.rs
index 8edf4ed65..d9da3db2d 100644
--- a/eth2/types/src/attester_slashing/builder.rs
+++ b/eth2/types/src/test_utils/testing_attester_slashing_builder.rs
@@ -2,9 +2,9 @@ use crate::*;
 use ssz::TreeHash;
 
 /// Builds an `AttesterSlashing`.
-pub struct AttesterSlashingBuilder();
+pub struct TestingAttesterSlashingBuilder();
 
-impl AttesterSlashingBuilder {
+impl TestingAttesterSlashingBuilder {
     /// Builds an `AttesterSlashing` that is a double vote.
     ///
     /// The `signer` function is used to sign the double-vote and accepts:
diff --git a/eth2/types/src/test_utils/testing_beacon_block_builder.rs b/eth2/types/src/test_utils/testing_beacon_block_builder.rs
index bbdc5046b..3ebd24b0a 100644
--- a/eth2/types/src/test_utils/testing_beacon_block_builder.rs
+++ b/eth2/types/src/test_utils/testing_beacon_block_builder.rs
@@ -1,9 +1,7 @@
 use crate::{
-    attester_slashing::AttesterSlashingBuilder,
-    proposer_slashing::ProposerSlashingBuilder,
     test_utils::{
-        TestingAttestationBuilder, TestingDepositBuilder, TestingTransferBuilder,
-        TestingVoluntaryExitBuilder,
+        TestingAttestationBuilder, TestingAttesterSlashingBuilder, TestingDepositBuilder,
+        TestingProposerSlashingBuilder, TestingTransferBuilder, TestingVoluntaryExitBuilder,
     },
     *,
 };
@@ -232,7 +230,7 @@ fn build_proposer_slashing(
         Signature::new(message, domain, secret_key)
     };
 
-    ProposerSlashingBuilder::double_vote(validator_index, signer, spec)
+    TestingProposerSlashingBuilder::double_vote(validator_index, signer, spec)
 }
 
 /// Builds an `AttesterSlashing` for some `validator_indices`.
@@ -253,5 +251,5 @@ fn build_double_vote_attester_slashing(
         Signature::new(message, domain, secret_keys[key_index])
     };
 
-    AttesterSlashingBuilder::double_vote(validator_indices, signer)
+    TestingAttesterSlashingBuilder::double_vote(validator_indices, signer)
 }
diff --git a/eth2/types/src/proposer_slashing/builder.rs b/eth2/types/src/test_utils/testing_proposer_slashing_builder.rs
similarity index 95%
rename from eth2/types/src/proposer_slashing/builder.rs
rename to eth2/types/src/test_utils/testing_proposer_slashing_builder.rs
index 472a76ec1..43ff3d0b7 100644
--- a/eth2/types/src/proposer_slashing/builder.rs
+++ b/eth2/types/src/test_utils/testing_proposer_slashing_builder.rs
@@ -2,9 +2,9 @@ use crate::*;
 use ssz::SignedRoot;
 
 /// Builds a `ProposerSlashing`.
-pub struct ProposerSlashingBuilder();
+pub struct TestingProposerSlashingBuilder();
 
-impl ProposerSlashingBuilder {
+impl TestingProposerSlashingBuilder {
     /// Builds a `ProposerSlashing` that is a double vote.
     ///
     /// The `signer` function is used to sign the double-vote and accepts: