diff --git a/Cargo.toml b/Cargo.toml
index a72d83c..92cffaf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,6 @@ resolver = "2"
 members = [
     "valuable",
     "valuable-derive",
-    "valuable-json",
     "valuable-serde",
     "tests",
 ]
diff --git a/valuable-json/Cargo.toml b/valuable-json/Cargo.toml
deleted file mode 100644
index 14a276d..0000000
--- a/valuable-json/Cargo.toml
+++ /dev/null
@@ -1,11 +0,0 @@
-[package]
-name = "valuable-json"
-version = "0.1.0"
-authors = ["Ning Sun <sunng@protonmail.com>"]
-edition = "2018"
-license = "MIT"
-description = "Valuable instrument for `serde_json::Value`"
-
-[dependencies]
-valuable = { version = "0.1", path = "../valuable", default-features = false }
-serde_json = "1"
diff --git a/valuable-json/src/lib.rs b/valuable-json/src/lib.rs
deleted file mode 100644
index c0d6aec..0000000
--- a/valuable-json/src/lib.rs
+++ /dev/null
@@ -1,36 +0,0 @@
-use serde_json::{Value as JsonValue};
-use valuable::{Valuable, Value, Visit};
-
-struct Json<'a>(&'a JsonValue);
-
-impl<'a> Valuable for Json<'a> {
-    fn as_value(&self) -> Value<'a> {
-        match self.0 {
-            // TODO: fixme
-            JsonValue::Array(ref array) => Value::Listable(array),
-            JsonValue::Bool(ref value) => Value::Bool(*value),
-            JsonValue::Number(ref num) => {
-                // TODO: check correctness for this
-                if num.is_f64() {
-                    Value::F64(num.as_f64().unwrap())
-                } else if num.is_i64() {
-                    Value::I64(num.as_i64().unwrap())
-                } else if num.is_u64() {
-                    Value::U64(num.as_u64().unwrap())
-                } else {
-                    unreachable!()
-                }
-            }
-            JsonValue::Null => Value::Unit,
-            JsonValue::String(ref s) => Value::String(s),
-            JsonValue::Object(ref object) => {
-                // TODO: make map valuable
-                Value::Mappable(object),
-            }
-        }
-    }
-
-    fn visit(&self, visit: &mut dyn Visit) {
-        //TODO:
-    }
-}
diff --git a/valuable/Cargo.toml b/valuable/Cargo.toml
index 4d7818a..ff4bacd 100644
--- a/valuable/Cargo.toml
+++ b/valuable/Cargo.toml
@@ -18,8 +18,12 @@ std = ["alloc"]
 # Provide imps for types in Rust's `alloc` library.
 alloc = []
 
+# Provides serde_json::Value instrument for valuable
+json = ["serde_json"]
+
 [dependencies]
 valuable-derive = { version = "0.1.0", optional = true, path = "../valuable-derive" }
+serde_json = { version = "1.0.46", optional = true }
 
 [dev-dependencies]
 criterion = "0.3"
diff --git a/valuable/src/json.rs b/valuable/src/json.rs
new file mode 100644
index 0000000..a106cb6
--- /dev/null
+++ b/valuable/src/json.rs
@@ -0,0 +1,68 @@
+use serde_json::{Map, Value as Json};
+
+use crate::{Mappable, Valuable, Value, Visit};
+
+impl Valuable for Json {
+    fn as_value(&self) -> Value<'_> {
+        match self {
+            Json::Array(ref array) => array.as_value(),
+            Json::Bool(ref value) => value.as_value(),
+            Json::Number(ref num) => {
+                // TODO: check correctness for this
+                if num.is_f64() {
+                    Value::F64(num.as_f64().unwrap())
+                } else if num.is_i64() {
+                    Value::I64(num.as_i64().unwrap())
+                } else if num.is_u64() {
+                    Value::U64(num.as_u64().unwrap())
+                } else {
+                    unreachable!()
+                }
+            }
+            Json::Null => Value::Unit,
+            Json::String(ref s) => s.as_value(),
+            Json::Object(ref object) => object.as_value(),
+        }
+    }
+
+    fn visit(&self, visit: &mut dyn Visit) {
+        match self {
+            Json::Array(ref array) => array.visit(visit),
+            Json::Bool(ref value) => value.visit(visit),
+            Json::Number(ref num) => {
+                // TODO: check correctness for this
+                if num.is_f64() {
+                    num.as_f64().unwrap().visit(visit)
+                } else if num.is_i64() {
+                    num.as_i64().unwrap().visit(visit)
+                } else if num.is_u64() {
+                    num.as_u64().unwrap().visit(visit)
+                } else {
+                    unreachable!()
+                }
+            }
+            Json::Null => Value::Unit.visit(visit),
+            Json::String(ref s) => s.visit(visit),
+            Json::Object(ref object) => object.visit(visit),
+        }
+    }
+}
+
+impl Valuable for Map<String, Json> {
+    fn as_value(&self) -> Value<'_> {
+        Value::Mappable(self)
+    }
+
+    fn visit(&self, visit: &mut dyn Visit) {
+        for (k, v) in self.iter() {
+            visit.visit_entry(k.as_value(), v.as_value());
+        }
+    }
+}
+
+impl Mappable for Map<String, Json> {
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
diff --git a/valuable/src/lib.rs b/valuable/src/lib.rs
index 7e61b5a..26c84e0 100644
--- a/valuable/src/lib.rs
+++ b/valuable/src/lib.rs
@@ -135,3 +135,6 @@ pub use visit::{visit, Visit};
 
 #[cfg(feature = "derive")]
 pub use valuable_derive::*;
+
+#[cfg(feature = "json")]
+mod json;