diff --git a/src/evm/executive.rs b/src/evm/executive.rs
index 383e79fc5..6fef7a6ba 100644
--- a/src/evm/executive.rs
+++ b/src/evm/executive.rs
@@ -47,13 +47,6 @@ impl Substate {
 	pub fn logs(&self) -> &[LogEntry] {
 		&self.logs
 	}
-
-	/// Appends another substate to this substate.
-	fn accrue(&mut self, s: Substate) {
-		self.suicides.extend(s.suicides.into_iter());
-		self.logs.extend(s.logs.into_iter());
-		self.refunds_count = self.refunds_count + s.refunds_count;
-	}
 }
 
 /// Transaction execution result.
@@ -425,17 +418,17 @@ impl<'a> Ext for Externalities<'a> {
 		self.state.code(address).unwrap_or(vec![])
 	}
 
-	fn ret(&mut self, gas: u64, data: &[u8]) -> Option<u64> {
+	fn ret(&mut self, gas: u64, data: &[u8]) -> Result<u64, EvmError> {
 		match &mut self.output {
 			&mut OutputPolicy::Return(ref mut slice) => unsafe {
 				let len = cmp::min(slice.len(), data.len());
 				ptr::copy(data.as_ptr(), slice.as_mut_ptr(), len);
-				Some(gas)
+				Ok(gas)
 			},
 			&mut OutputPolicy::InitContract => {
 				let return_cost = data.len() as u64 * self.schedule.create_data_gas as u64;
 				if return_cost > gas {
-					return None;
+					return Err(EvmError::OutOfGas);
 				}
 				let mut code = vec![];
 				code.reserve(data.len());
@@ -445,7 +438,7 @@ impl<'a> Ext for Externalities<'a> {
 				}
 				let address = &self.params.address;
 				self.state.init_code(address, code);
-				Some(gas - return_cost)
+				Ok(gas - return_cost)
 			}
 		}
 	}
diff --git a/src/evm/ext.rs b/src/evm/ext.rs
index 9ffebc605..33f89e32f 100644
--- a/src/evm/ext.rs
+++ b/src/evm/ext.rs
@@ -47,7 +47,7 @@ pub trait Ext {
 
 	/// Should be called when transaction calls `RETURN` opcode.
 	/// Returns gas_left if cost of returning the data is not too high.
-	fn ret(&mut self, gas: u64, data: &[u8]) -> Option<u64>;
+	fn ret(&mut self, gas: u64, data: &[u8]) -> Result<u64, EvmError>;
 
 	/// Should be called when contract commits suicide.
 	fn suicide(&mut self);
diff --git a/src/evm/jit.rs b/src/evm/jit.rs
index 6272d87f7..3f0dff6ed 100644
--- a/src/evm/jit.rs
+++ b/src/evm/jit.rs
@@ -347,10 +347,7 @@ impl evm::Evm for JitEvm {
 		
 		match res {
 			evmjit::ReturnCode::Stop => Ok(U256::from(context.gas_left())),
-			evmjit::ReturnCode::Return => match ext.ret(context.gas_left(), context.output_data()) {
-				Some(gas_left) => Ok(U256::from(gas_left)),
-				None => Err(evm::EvmError::OutOfGas)
-			},
+			evmjit::ReturnCode::Return => ext.ret(context.gas_left(), context.output_data()).map(|gas_left| U256::from(gas_left)),
 			evmjit::ReturnCode::Suicide => { 
 				// what if there is a suicide and we run out of gas just after?
 				ext.suicide();