diff --git a/ethcore/res/wasm-tests b/ethcore/res/wasm-tests
index d4920761f..e5fcae4e9 160000
--- a/ethcore/res/wasm-tests
+++ b/ethcore/res/wasm-tests
@@ -1 +1 @@
-Subproject commit d4920761f959a785c3ec15cf2848fc75795eb2d4
+Subproject commit e5fcae4e9c2a570f293a22baa4d78d9f4b391a0f
diff --git a/ethcore/wasm/src/env.rs b/ethcore/wasm/src/env.rs
index 1a2f5fd3b..1004f3526 100644
--- a/ethcore/wasm/src/env.rs
+++ b/ethcore/wasm/src/env.rs
@@ -25,12 +25,12 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 	Static(
 		"_storage_read",
 		&[I32; 2],
-		Some(I32),
+		None,
 	),
 	Static(
 		"_storage_write",
 		&[I32; 2],
-		Some(I32),
+		None,
 	),
 	Static(
 		"_balance",
diff --git a/ethcore/wasm/src/runtime.rs b/ethcore/wasm/src/runtime.rs
index 3c2bd101e..0782876b5 100644
--- a/ethcore/wasm/src/runtime.rs
+++ b/ethcore/wasm/src/runtime.rs
@@ -168,7 +168,7 @@ impl<'a, 'b> Runtime<'a, 'b> {
 
 		self.ext.set_storage(key, val).map_err(|_| UserTrap::StorageUpdateError)?;
 
-		Ok(Some(0i32.into()))
+		Ok(None)
 	}
 
 	/// Read from the storage to wasm memory
@@ -184,7 +184,7 @@ impl<'a, 'b> Runtime<'a, 'b> {
 
 		self.memory.set(val_ptr as u32, &*val)?;
 
-		Ok(Some(0.into()))
+		Ok(None)
 	}
 
 	/// Fetches balance for address
diff --git a/ethcore/wasm/src/tests.rs b/ethcore/wasm/src/tests.rs
index 9f8b7ddec..f5738871b 100644
--- a/ethcore/wasm/src/tests.rs
+++ b/ethcore/wasm/src/tests.rs
@@ -112,7 +112,7 @@ fn logger() {
 		U256::from(1_000_000_000),
 		"Logger sets 0x04 key to the trasferred value"
 	);
-	assert_eq!(gas_left, U256::from(19_143));
+	assert_eq!(gas_left, U256::from(19_147));
 }
 
 // This test checks if the contract can allocate memory and pass pointer to the result stream properly.
@@ -180,7 +180,7 @@ fn dispersion() {
 		result,
 		vec![0u8, 0, 125, 11, 197, 7, 255, 8, 19, 0]
 	);
-	assert_eq!(gas_left, U256::from(96_961));
+	assert_eq!(gas_left, U256::from(96_393));
 }
 
 #[test]
@@ -208,7 +208,7 @@ fn suicide_not() {
 		result,
 		vec![0u8]
 	);
-	assert_eq!(gas_left, U256::from(97_290));
+	assert_eq!(gas_left, U256::from(96_725));
 }
 
 #[test]
@@ -240,7 +240,7 @@ fn suicide() {
 	};
 
 	assert!(ext.suicides.contains(&refund));
-	assert_eq!(gas_left, U256::from(97_249));
+	assert_eq!(gas_left, U256::from(96_687));
 }
 
 #[test]
@@ -270,7 +270,7 @@ fn create() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Create,
-			gas: U256::from(65_903),
+			gas: U256::from(65_899),
 			sender_address: None,
 			receive_address: None,
 			value: Some(1_000_000_000.into()),
@@ -278,7 +278,7 @@ fn create() {
 			code_address: None,
 		}
 	));
-	assert_eq!(gas_left, U256::from(65_896));
+	assert_eq!(gas_left, U256::from(65_892));
 }
 
 
@@ -393,7 +393,7 @@ fn realloc() {
 		}
 	};
 	assert_eq!(result, vec![0u8; 2]);
-	assert_eq!(gas_left, U256::from(97_278));
+	assert_eq!(gas_left, U256::from(96_723));
 }
 
 // Tests that contract's ability to read from a storage
@@ -419,7 +419,7 @@ fn storage_read() {
 	};
 
 	assert_eq!(Address::from(&result[12..32]), address);
-	assert_eq!(gas_left, U256::from(99_706));
+	assert_eq!(gas_left, U256::from(99_767));
 }
 
 // Tests keccak calculation
@@ -445,7 +445,7 @@ fn keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(82_009));
+	assert_eq!(gas_left, U256::from(81_446));
 }
 
 // memcpy test.
@@ -477,7 +477,7 @@ fn memcpy() {
 	};
 
 	assert_eq!(result, test_payload);
-	assert_eq!(gas_left, U256::from(72_773));
+	assert_eq!(gas_left, U256::from(72_216));
 }
 
 // memmove test.
@@ -509,7 +509,7 @@ fn memmove() {
 	};
 
 	assert_eq!(result, test_payload);
-	assert_eq!(gas_left, U256::from(72_773));
+	assert_eq!(gas_left, U256::from(72_216));
 }
 
 // memset test
@@ -534,7 +534,7 @@ fn memset() {
 	};
 
 	assert_eq!(result, vec![228u8; 8192]);
-	assert_eq!(gas_left, U256::from(72_763));
+	assert_eq!(gas_left, U256::from(72_196));
 }
 
 macro_rules! reqrep_test {
@@ -591,7 +591,7 @@ fn math_add() {
 		U256::from_dec_str("1888888888888888888888888888887").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(96_084));
+	assert_eq!(gas_left, U256::from(95_524));
 }
 
 // multiplication
@@ -613,7 +613,7 @@ fn math_mul() {
 		U256::from_dec_str("888888888888888888888888888887111111111111111111111111111112").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(95_234));
+	assert_eq!(gas_left, U256::from(94_674));
 }
 
 // subtraction
@@ -635,7 +635,7 @@ fn math_sub() {
 		U256::from_dec_str("111111111111111111111111111111").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(96_076));
+	assert_eq!(gas_left, U256::from(95_516));
 }
 
 // subtraction with overflow
@@ -677,7 +677,7 @@ fn math_div() {
 		U256::from_dec_str("1125000").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(89_074));
+	assert_eq!(gas_left, U256::from(88_514));
 }
 
 // This test checks the ability of wasm contract to invoke
@@ -765,7 +765,7 @@ fn externs() {
 		"Gas limit requested and returned does not match"
 	);
 
-	assert_eq!(gas_left, U256::from(95_291));
+	assert_eq!(gas_left, U256::from(94_733));
 }
 
 #[test]
@@ -791,7 +791,7 @@ fn embedded_keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(82_009));
+	assert_eq!(gas_left, U256::from(81_446));
 }
 
 /// This test checks the correctness of log extern
@@ -826,5 +826,5 @@ fn events() {
 	assert_eq!(&log_entry.data, b"gnihtemos");
 
 	assert_eq!(&result, b"gnihtemos");
-	assert_eq!(gas_left, U256::from(80_199));
+	assert_eq!(gas_left, U256::from(79_637));
 }