diff --git a/crates/e2e-move-tests/src/tests/output.rs b/crates/e2e-move-tests/src/tests/output.rs
index 2ffd4ad0..f28abb4e 100644
--- a/crates/e2e-move-tests/src/tests/output.rs
+++ b/crates/e2e-move-tests/src/tests/output.rs
@@ -58,7 +58,7 @@ fn test_output() {
         vec![],
         ExpectedOutput::new(
             VMStatus::Executed,
-            Some("[\"123\"]".to_string()),
+            Some("\"123\"".to_string()),
             None,
             None,
         ),
@@ -72,7 +72,7 @@ fn test_output() {
         vec![],
         ExpectedOutput::new(
             VMStatus::Executed,
-            Some("[[\"123\"]]".to_string()),
+            Some("[\"123\"]".to_string()),
             None,
             None,
         ),
@@ -84,7 +84,7 @@ fn test_output() {
         "0x2::test::option_none",
         vec![],
         vec![],
-        ExpectedOutput::new(VMStatus::Executed, Some("[]".to_string()), None, None),
+        ExpectedOutput::new(VMStatus::Executed, Some("null".to_string()), None, None),
     );
     tests.push(test_option_none);
 
diff --git a/crates/vm/src/json/json_to_move.rs b/crates/vm/src/json/json_to_move.rs
index 39138038..9d9991a3 100644
--- a/crates/vm/src/json/json_to_move.rs
+++ b/crates/vm/src/json/json_to_move.rs
@@ -189,24 +189,16 @@ pub(crate) fn convert_json_value_to_move_value<S: StateView>(
             let full_name = format!("{}::{}", id.module_id.short_str_lossless(), id.name);
             match full_name.as_str() {
                 "0x1::option::Option" => {
-                    let json_vals = json_val
-                        .as_array()
-                        .ok_or_else(deserialization_error)?
-                        .to_owned();
-
-                    if json_vals.is_empty() {
+                    if json_val.is_null() {
                         return Ok(MoveValue::Vector(vec![]));
-                    } else if json_vals.len() == 1 {
-                        let json_val = json_vals.into_iter().next().unwrap();
-                        return Ok(MoveValue::Vector(vec![convert_json_value_to_move_value(
-                            state_view,
-                            ty,
-                            json_val,
-                            depth + 1,
-                        )?]));
                     }
 
-                    return Err(deserialization_error_with_msg("invalid option value"));
+                    return Ok(MoveValue::Vector(vec![convert_json_value_to_move_value(
+                        state_view,
+                        ty,
+                        json_val,
+                        depth + 1,
+                    )?]));
                 }
                 "0x1::object::Object" => {
                     let addr = AccountAddress::from_hex_literal(
@@ -614,7 +606,7 @@ mod json_arg_testing {
             ty_args: Arc::new(vec![Type::Address]),
             ability: AbilityInfo::struct_(AbilitySet::ALL),
         };
-        let arg = b"[\"0x1\"]";
+        let arg = b"\"0x1\"";
         let result = deserialize_json_args(&state_view, &ty, arg).unwrap();
         assert_eq!(
             result,
@@ -622,7 +614,7 @@ mod json_arg_testing {
         );
 
         // invalid inner value
-        let arg = b"[\"0xgg\"]";
+        let arg = b"\"0xgg\"";
         _ = deserialize_json_args(&state_view, &ty, arg).unwrap_err();
     }
 
@@ -639,7 +631,7 @@ mod json_arg_testing {
             ty_args: Arc::new(vec![Type::Address]),
             ability: AbilityInfo::struct_(AbilitySet::ALL),
         };
-        let arg = b"[]";
+        let arg = b"null";
         let result = deserialize_json_args(&state_view, &ty, arg).unwrap();
         assert_eq!(
             result,
diff --git a/crates/vm/src/json/move_to_json.rs b/crates/vm/src/json/move_to_json.rs
index 0b14c022..101eae36 100644
--- a/crates/vm/src/json/move_to_json.rs
+++ b/crates/vm/src/json/move_to_json.rs
@@ -149,12 +149,9 @@ fn convert_option_to_json_value(val: &MoveValue, depth: usize) -> VMResult<JSONV
     Ok(match val {
         MoveValue::Vector(elem) => {
             if elem.is_empty() {
-                JSONValue::Array(vec![])
+                JSONValue::Null
             } else {
-                JSONValue::Array(vec![convert_move_value_to_json_value(
-                    elem.first().unwrap(),
-                    depth + 1,
-                )?])
+                convert_move_value_to_json_value(elem.first().unwrap(), depth + 1)?
             }
         }
         _ => unreachable!(),
@@ -267,7 +264,7 @@ mod move_to_json_tests {
             )],
         });
         let val = convert_move_value_to_json_value(&mv, 1).unwrap();
-        assert_eq!(val, json!([123u8]));
+        assert_eq!(val, json!(123u8));
 
         // option none
         let mv = MoveValue::Struct(MoveStruct::WithTypes {
@@ -280,7 +277,7 @@ mod move_to_json_tests {
             fields: vec![(ident_str!("vec").into(), MoveValue::Vector(vec![]))],
         });
         let val = convert_move_value_to_json_value(&mv, 1).unwrap();
-        assert_eq!(val, json!([]));
+        assert_eq!(val, json!(null));
 
         // decimal128
         const DECIMAL_SCALE: u128 = 1_000_000_000_000_000_000;
diff --git a/precompile/binaries/stdlib/minitswap.mv b/precompile/binaries/stdlib/minitswap.mv
index 69ce2466..13826d2b 100644
Binary files a/precompile/binaries/stdlib/minitswap.mv and b/precompile/binaries/stdlib/minitswap.mv differ