diff --git a/Cargo.lock b/Cargo.lock
index 7e4a572e..86b0b76a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1044,7 +1044,7 @@ dependencies = [
 [[package]]
 name = "ethabi"
 version = "16.0.0"
-source = "git+https://github.com/rust-ethereum/ethabi?branch=master#7f4bb3d6164775928485b2bad2f6e130a96f438e"
+source = "git+https://github.com/rust-ethereum/ethabi?branch=master#199e307462ea6ad17c3ff48dcba8aa42b23cb2c3"
 dependencies = [
  "ethereum-types",
  "hex",
diff --git a/ethers-contract/ethers-contract-derive/src/abigen.rs b/ethers-contract/ethers-contract-derive/src/abigen.rs
index 43124b95..86b31a5e 100644
--- a/ethers-contract/ethers-contract-derive/src/abigen.rs
+++ b/ethers-contract/ethers-contract-derive/src/abigen.rs
@@ -269,7 +269,7 @@ impl Parse for Method {
                 //   affect its signature.
                 outputs: vec![],
                 state_mutability: StateMutability::NonPayable,
-                constant: false,
+                constant: None,
             }
         };
         let signature = function.abi_signature();
diff --git a/ethers-contract/ethers-contract-derive/src/call.rs b/ethers-contract/ethers-contract-derive/src/call.rs
index f55b791e..7a6903e7 100644
--- a/ethers-contract/ethers-contract-derive/src/call.rs
+++ b/ethers-contract/ethers-contract-derive/src/call.rs
@@ -47,7 +47,7 @@ pub(crate) fn derive_eth_call_impl(input: DeriveInput) -> TokenStream {
                     name: function_call_name.clone(),
                     inputs,
                     outputs: vec![],
-                    constant: false,
+                    constant: None,
                     state_mutability: Default::default(),
                 }
             } else {
diff --git a/ethers-core/src/abi/human_readable.rs b/ethers-core/src/abi/human_readable.rs
index 7375a1b9..5c24ac24 100644
--- a/ethers-core/src/abi/human_readable.rs
+++ b/ethers-core/src/abi/human_readable.rs
@@ -317,7 +317,7 @@ impl AbiParser {
 
         Ok(
             #[allow(deprecated)]
-            Function { name, inputs, outputs, state_mutability, constant: false },
+            Function { name, inputs, outputs, state_mutability, constant: None },
         )
     }