diff --git a/account_manager/src/lib.rs b/account_manager/src/lib.rs
index 694cf80ef2..7070cc87ab 100644
--- a/account_manager/src/lib.rs
+++ b/account_manager/src/lib.rs
@@ -3,7 +3,7 @@ mod cli;
 use clap::ArgMatches;
 use deposit_contract::DEPOSIT_GAS;
 use environment::{Environment, RuntimeContext};
-use eth2_testnet::Eth2TestnetDir;
+use eth2_testnet::{Eth2TestnetDir, TempDir};
 use futures::{future, stream::unfold, Future, IntoFuture, Stream};
 use rayon::prelude::*;
 use slog::{crit, error, info, Logger};
@@ -174,7 +174,9 @@ fn run_new_validator_subcommand<T: EthSpec>(
             "eth1_node_http_endpoint" => eth1_endpoint
         );
 
-        let deposit_contract = if let Some(testnet_dir_str) = matches.value_of("testnet-dir") {
+        let eth2_testnet_dir: Eth2TestnetDir<T> = if let Some(testnet_dir_str) =
+            matches.value_of("testnet-dir")
+        {
             let testnet_dir = testnet_dir_str
                 .parse::<PathBuf>()
                 .map_err(|e| format!("Unable to parse testnet-dir: {}", e))?;
@@ -192,23 +194,31 @@ fn run_new_validator_subcommand<T: EthSpec>(
                 "testnet_dir" => format!("{:?}", &testnet_dir)
             );
 
-            let eth2_testnet_dir: Eth2TestnetDir<T> = Eth2TestnetDir::load(testnet_dir.clone())
-                .map_err(|e| format!("Failed to load testnet dir at {:?}: {}", testnet_dir, e))?;
-
-            // Convert from `types::Address` to `web3::types::Address`.
-            Address::from_slice(
-                eth2_testnet_dir
-                    .deposit_contract_address()?
-                    .as_fixed_bytes(),
-            )
+            Eth2TestnetDir::load(testnet_dir.clone())
+                .map_err(|e| format!("Failed to load testnet dir at {:?}: {}", testnet_dir, e))?
         } else {
-            matches
-                .value_of("deposit-contract")
-                .ok_or_else(|| "No --deposit-contract or --testnet-dir".to_string())?
-                .parse::<Address>()
-                .map_err(|e| format!("Unable to parse deposit-contract: {}", e))?
+            let temp_dir = TempDir::new("lighthouse-account-manager")
+                .map_err(|e| format!("Unable to create temporary directory: {}", e))?;
+
+            info!(log, "Using default deposit contract address");
+
+            let testnet_dir = PathBuf::from(temp_dir.path());
+
+            Eth2TestnetDir::load(testnet_dir.clone()).map_err(|e| {
+                format!(
+                    "Failed to load default testnet dir at {:?}: {}",
+                    testnet_dir, e
+                )
+            })?
         };
 
+        // Convert from `types::Address` to `web3::types::Address`.
+        let deposit_contract = Address::from_slice(
+            eth2_testnet_dir
+                .deposit_contract_address()?
+                .as_fixed_bytes(),
+        );
+
         if let Err(()) = env.runtime().block_on(deposit_validators(
             context.clone(),
             eth1_endpoint.to_string(),
diff --git a/eth2/utils/eth2_testnet/Cargo.toml b/eth2/utils/eth2_testnet/Cargo.toml
index cc04cb739d..213bbee5b6 100644
--- a/eth2/utils/eth2_testnet/Cargo.toml
+++ b/eth2/utils/eth2_testnet/Cargo.toml
@@ -6,12 +6,10 @@ edition = "2018"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
-[dev-dependencies]
-tempdir = "0.3"
-
 [dependencies]
 serde = "1.0"
 serde_yaml = "0.8"
 types = { path = "../../types"}
 eth2-libp2p = { path = "../../../beacon_node/eth2-libp2p"}
 eth2_ssz = { path = "../ssz"}
+tempdir = "0.3"
diff --git a/eth2/utils/eth2_testnet/src/lib.rs b/eth2/utils/eth2_testnet/src/lib.rs
index a92442606b..414857c448 100644
--- a/eth2/utils/eth2_testnet/src/lib.rs
+++ b/eth2/utils/eth2_testnet/src/lib.rs
@@ -14,6 +14,8 @@ use std::io::{Read, Write};
 use std::path::PathBuf;
 use types::{Address, BeaconState, EthSpec, YamlConfig};
 
+pub use tempdir::TempDir;
+
 pub const ADDRESS_FILE: &str = "deposit_contract.txt";
 pub const DEPLOY_BLOCK_FILE: &str = "deploy_block.txt";
 pub const BOOT_ENR_FILE: &str = "boot_enr.yaml";