diff --git a/Cargo.lock b/Cargo.lock
index 372deb14..f8fa2751 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1075,6 +1075,7 @@ dependencies = [
  "serde",
  "serde-aux",
  "serde_json",
+ "serial_test",
  "thiserror",
  "tokio",
 ]
@@ -1098,6 +1099,7 @@ dependencies = [
  "reqwest",
  "serde",
  "serde_json",
+ "serial_test",
  "thiserror",
  "tokio",
  "tracing",
@@ -2794,6 +2796,28 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serial_test"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0bccbcf40c8938196944a3da0e133e031a33f4d6b72db3bda3cc556e361905d"
+dependencies = [
+ "lazy_static",
+ "parking_lot",
+ "serial_test_derive",
+]
+
+[[package]]
+name = "serial_test_derive"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2acd6defeddb41eb60bb468f8825d0cfd0c2a76bc03bfd235b6a1dc4f6a1ad5"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "sha-1"
 version = "0.9.8"
diff --git a/ethers-etherscan/Cargo.toml b/ethers-etherscan/Cargo.toml
index 9139dfe6..ed9dd2a9 100644
--- a/ethers-etherscan/Cargo.toml
+++ b/ethers-etherscan/Cargo.toml
@@ -23,6 +23,7 @@ thiserror = "1.0.29"
 
 [dev-dependencies]
 tokio = { version = "1.5", features = ["macros", "rt-multi-thread"] }
+serial_test = "0.5.1"
 
 [package.metadata.docs.rs]
 all-features = true
diff --git a/ethers-etherscan/src/contract.rs b/ethers-etherscan/src/contract.rs
index faf50661..d9e18bd3 100644
--- a/ethers-etherscan/src/contract.rs
+++ b/ethers-etherscan/src/contract.rs
@@ -254,7 +254,10 @@ mod tests {
     use crate::{contract::VerifyContract, Client};
     use ethers_core::types::Chain;
 
+    use serial_test::serial;
+
     #[tokio::test]
+    #[serial]
     #[ignore]
     async fn can_fetch_contract_abi() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
@@ -266,6 +269,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     #[ignore]
     async fn can_fetch_contract_source_code() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
@@ -277,6 +281,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     #[ignore]
     async fn can_verify_contract() {
         // TODO this needs further investigation
diff --git a/ethers-etherscan/src/gas.rs b/ethers-etherscan/src/gas.rs
index 0137ac0f..4d3c66dd 100644
--- a/ethers-etherscan/src/gas.rs
+++ b/ethers-etherscan/src/gas.rs
@@ -1,9 +1,10 @@
 use std::{collections::HashMap, str::FromStr};
 
-use ethers_core::types::U256;
 use serde::{de, Deserialize};
 use serde_aux::prelude::*;
 
+use ethers_core::types::U256;
+
 use crate::{Client, EtherscanError, Response, Result};
 
 #[derive(Deserialize)]
@@ -69,11 +70,14 @@ impl Client {
 
 #[cfg(test)]
 mod tests {
+    use serial_test::serial;
+
     use ethers_core::types::Chain;
 
     use super::*;
 
     #[tokio::test]
+    #[serial]
     async fn gas_estimate_success() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
@@ -83,6 +87,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     async fn gas_estimate_error() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
@@ -92,6 +97,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     async fn gas_oracle_success() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
diff --git a/ethers-etherscan/src/lib.rs b/ethers-etherscan/src/lib.rs
index 4c8d8e13..689e8358 100644
--- a/ethers-etherscan/src/lib.rs
+++ b/ethers-etherscan/src/lib.rs
@@ -1,16 +1,18 @@
 //! Bindings for [etherscan.io web api](https://docs.etherscan.io/)
 
+use std::borrow::Cow;
+
+use reqwest::{header, Url};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
+
+use errors::EtherscanError;
+use ethers_core::{abi::Address, types::Chain};
+
 pub mod contract;
 pub mod errors;
 pub mod gas;
 pub mod transaction;
 
-use errors::EtherscanError;
-use ethers_core::{abi::Address, types::Chain};
-use reqwest::{header, Url};
-use serde::{de::DeserializeOwned, Deserialize, Serialize};
-use std::borrow::Cow;
-
 pub type Result<T> = std::result::Result<T, EtherscanError>;
 
 /// The Etherscan.io API client.
@@ -174,9 +176,10 @@ struct Query<'a, T: Serialize> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{Client, EtherscanError};
     use ethers_core::types::Chain;
 
+    use crate::{Client, EtherscanError};
+
     #[test]
     fn chain_not_supported() {
         let err = Client::new_from_env(Chain::XDai).unwrap_err();
diff --git a/ethers-etherscan/src/transaction.rs b/ethers-etherscan/src/transaction.rs
index 260f70f3..69b1564b 100644
--- a/ethers-etherscan/src/transaction.rs
+++ b/ethers-etherscan/src/transaction.rs
@@ -52,10 +52,14 @@ impl Client {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use serial_test::serial;
+
     use crate::Chain;
 
+    use super::*;
+
     #[tokio::test]
+    #[serial]
     async fn check_contract_execution_status_success() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
@@ -69,6 +73,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     async fn check_contract_execution_status_error() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
@@ -84,6 +89,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     async fn check_transaction_receipt_status_success() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
@@ -97,6 +103,7 @@ mod tests {
     }
 
     #[tokio::test]
+    #[serial]
     async fn check_transaction_receipt_status_failed() {
         let client = Client::new_from_env(Chain::Mainnet).unwrap();
 
diff --git a/ethers-middleware/Cargo.toml b/ethers-middleware/Cargo.toml
index 714a7a28..64e20d3e 100644
--- a/ethers-middleware/Cargo.toml
+++ b/ethers-middleware/Cargo.toml
@@ -43,6 +43,7 @@ rand = { version = "0.8.4", default-features = false }
 ethers-providers = { version = "^0.6.0", path = "../ethers-providers", default-features = false, features = ["ws", "rustls"] }
 once_cell = "1.8.0"
 ethers-solc = { version = "^0.1.0", path = "../ethers-solc", default-features = false }
+serial_test = "0.5.1"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
 tokio = { version = "1.5", default-features = false, features = ["rt", "macros", "time"] }
diff --git a/ethers-middleware/tests/gas_oracle.rs b/ethers-middleware/tests/gas_oracle.rs
index 916ca036..49560319 100644
--- a/ethers-middleware/tests/gas_oracle.rs
+++ b/ethers-middleware/tests/gas_oracle.rs
@@ -10,6 +10,7 @@ use ethers_middleware::gas_oracle::{
     GasOracleMiddleware,
 };
 use ethers_providers::{Http, Middleware, Provider};
+use serial_test::serial;
 
 #[derive(Debug)]
 struct FakeGasOracle {
@@ -60,6 +61,7 @@ async fn eth_gas_station() {
 }
 
 #[tokio::test]
+#[serial]
 async fn etherscan() {
     let etherscan_client = ethers_etherscan::Client::new_from_env(Chain::Mainnet).unwrap();