diff --git a/contract/contract_module.c b/contract/contract_module.c
index da9b259be..3fd1ac152 100644
--- a/contract/contract_module.c
+++ b/contract/contract_module.c
@@ -46,7 +46,7 @@ static int set_value(lua_State *L, const char *str) {
 			luaL_error(L, "not enough memory");
 		}
 		lua_pushstring(L, str);
-		free (str);
+		free(str);
 		break;
 	}
 	default:
@@ -280,6 +280,14 @@ static int moduleBalance(lua_State *L) {
 	return 1;
 }
 
+static int moduleGasLeft(lua_State *L) {
+	char str[64];
+	// do not charge gas for this call for easier calculations
+	snprintf(str, sizeof(str), "%llu", lua_gasget(L));
+	lua_pushstring(L, str);
+	return 1;
+}
+
 static int modulePcall(lua_State *L) {
 	int argc = lua_gettop(L) - 1;
 	int service = getLuaExecContext(L);
@@ -492,7 +500,20 @@ static const luaL_Reg deploy_call_meta[] = {
 	{NULL, NULL}
 };
 
-static const luaL_Reg contract_lib[] = {
+static const luaL_Reg contract_lib_v3[] = {
+	{"balance", moduleBalance},
+	{"send", moduleSend},
+	{"pcall", modulePcall},
+	{"event", moduleEvent},
+	{"stake", moduleStake},
+	{"unstake", moduleUnstake},
+	{"vote", moduleVote},
+	{"voteDao", moduleVoteDao},
+	{NULL, NULL}
+};
+
+static const luaL_Reg contract_lib_v4[] = {
+	{"gasLeft", moduleGasLeft},
 	{"balance", moduleBalance},
 	{"send", moduleSend},
 	{"pcall", modulePcall},
@@ -506,7 +527,11 @@ static const luaL_Reg contract_lib[] = {
 
 int luaopen_contract(lua_State *L) {
 
-	luaL_register(L, contract_str, contract_lib);
+	if (vm_is_hardfork(L, 4)) {
+		luaL_register(L, contract_str, contract_lib_v4);
+	} else {
+		luaL_register(L, contract_str, contract_lib_v3);
+	}
 
 	lua_createtable(L, 0, 3);
 	luaL_register(L, NULL, call_methods);
diff --git a/contract/vm_dummy/test_files/contract_gasleft.lua b/contract/vm_dummy/test_files/contract_gasleft.lua
new file mode 100644
index 000000000..654752f81
--- /dev/null
+++ b/contract/vm_dummy/test_files/contract_gasleft.lua
@@ -0,0 +1,42 @@
+
+function test1()
+  local gas_before = bignum.number(contract.gasLeft())
+  local a = 0
+  for i = 1,10 do
+    a = a + i
+  end
+  local gas_after = bignum.number(contract.gasLeft())
+  local used_gas = gas_before - gas_after
+  return gas_before, gas_after, used_gas
+end
+
+function test2(...)
+  local gas_before = bignum.number(contract.gasLeft())
+  contract.call(...)
+  local gas_after = bignum.number(contract.gasLeft())
+  local used_gas = gas_before - gas_after
+  return gas_before, gas_after, used_gas
+end
+
+function test3(address)
+  local g1 = contract.gasLeft()
+  local g2, g3 = contract.call(address, "test")
+  local g4 = contract.gasLeft()
+  return g1, g2, g3, g4
+end
+
+function callback()
+  return contract.gasLeft()
+end
+
+abi.register(test1, test2, test3, callback)
+
+--- this is used in another contract
+
+function test()
+  local g1 = contract.gasLeft()
+  local g2 = contract.call(system.getSender(), "callback")
+  return g1, g2
+end
+
+abi.register(test)
diff --git a/contract/vm_dummy/test_files/loop.lua b/contract/vm_dummy/test_files/loop.lua
new file mode 100644
index 000000000..5748fd770
--- /dev/null
+++ b/contract/vm_dummy/test_files/loop.lua
@@ -0,0 +1,10 @@
+
+function loop(n)
+  local a = 0
+  for i = 1,n do
+    a = a + i
+  end
+  return a
+end
+
+abi.register(loop)
diff --git a/contract/vm_dummy/vm_dummy_pub_test.go b/contract/vm_dummy/vm_dummy_pub_test.go
index 544d60c0b..cc210f4c4 100644
--- a/contract/vm_dummy/vm_dummy_pub_test.go
+++ b/contract/vm_dummy/vm_dummy_pub_test.go
@@ -794,3 +794,45 @@ func TestTypeBigTable(t *testing.T) {
 		require.NoErrorf(t, err, "failed to call tx")
 	}
 }
+
+func TestContractGasLeft(t *testing.T) {
+	code1 := readLuaCode(t, "contract_gasleft.lua")
+	code2 := readLuaCode(t, "loop.lua")
+
+	for version := int32(4); version <= max_version; version++ {
+		bc, err := LoadDummyChain(SetHardForkVersion(version), SetPubNet())
+		require.NoErrorf(t, err, "failed to create dummy chain")
+		defer bc.Release()
+
+		err = bc.ConnectBlock(
+			NewLuaTxAccount("user1", 1, types.Aergo),
+			NewLuaTxDeploy("user1", "A", 0, code1),
+			NewLuaTxDeploy("user1", "B", 0, code1),
+			NewLuaTxDeploy("user1", "loop", 0, code2),
+		)
+		require.NoErrorf(t, err, "failed to connect new block")
+
+		tx := NewLuaTxCall("user1", "A", 0, `{"Name":"test1", "Args":[]}`)
+		err = bc.ConnectBlock(tx)
+		require.NoErrorf(t, err, "failed to connect new block")
+		receipt := bc.GetReceipt(tx.Hash())
+		expected := `[{"_bignum":"18446744073709548605"},{"_bignum":"18446744073709548172"},{"_bignum":"433"}]`
+		require.Equalf(t, expected, receipt.GetRet(), "contract call ret error")
+
+		tx = NewLuaTxCall("user1", "A", 0, fmt.Sprintf(`{"Name":"test2", "Args":["%s","loop",10]}`, nameToAddress("loop")))
+		err = bc.ConnectBlock(tx)
+		require.NoErrorf(t, err, "failed to connect new block")
+		receipt = bc.GetReceipt(tx.Hash())
+		expected = `[{"_bignum":"18446744073709547285"},{"_bignum":"18446744073709543337"},{"_bignum":"3948"}]`
+		require.Equalf(t, expected, receipt.GetRet(), "contract call ret error")
+
+		// make an external call and a callback, like this: A -> B -> A
+		tx = NewLuaTxCall("user1", "A", 0, fmt.Sprintf(`{"Name":"test3", "Args":["%s"]}`, nameToAddress("B")))
+		err = bc.ConnectBlock(tx)
+		require.NoErrorf(t, err, "failed to connect new block")
+		receipt = bc.GetReceipt(tx.Hash())
+		expected = `["18446744073709548612","18446744073709543257","18446744073709536656","18446744073709535921"]`
+		require.Equalf(t, expected, receipt.GetRet(), "contract call ret error")
+
+	}
+}