diff --git a/.travis.yml b/.travis.yml
index 6c5cb10..cf4193c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,4 @@
+dist: xenial
 language: rust
 rust:
   - nightly
@@ -10,6 +11,7 @@ addons:
   apt:
     packages:
     - libgtk-3-dev
+    - libmount-dev
 script:
   - rustc --version
   - cargo build
diff --git a/Cargo.toml b/Cargo.toml
index ed35a4e..e1e686d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,5 +16,5 @@ name = "javascriptcore"
 git = "https://github.com/gtk-rs/glib"
 
 [dependencies.javascriptcore-rs-sys]
-git = "https://github.com/gtk-rs/javascriptcore-rs"
+path = "./javascriptcore-sys"
 version = "0.1.1"
diff --git a/javascriptcore-sys/src/lib.rs b/javascriptcore-sys/src/lib.rs
index 5f8bedb..2d29f65 100644
--- a/javascriptcore-sys/src/lib.rs
+++ b/javascriptcore-sys/src/lib.rs
@@ -6,6 +6,8 @@ extern crate libc;
 
 use libc::{c_char, c_double, c_void};
 
+pub type JSCValue = *mut c_void;
+pub type JSCContext = *mut c_void;
 pub type JSGlobalContextRef = *mut c_void;
 pub type JSValueRef = *mut c_void;
 pub type JSStringRef = *mut c_void;
diff --git a/src/lib.rs b/src/lib.rs
index 39caf57..78316c6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,48 +10,52 @@ use std::ptr;
 use glib::translate::{FromGlibPtrFull, FromGlibPtrNone};
 use javascriptcore_sys::*;
 
-pub struct GlobalContext {
+pub struct GlobalContextRef {
     raw: JSGlobalContextRef,
 }
 
-pub struct Value {
+pub struct ValueRef {
     raw: JSValueRef,
 }
 
-impl Value {
-    pub fn is_boolean(&self, context: &GlobalContext) -> bool {
+pub struct Value {
+    raw: JSCValue,
+}
+
+impl ValueRef {
+    pub fn is_boolean(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsBoolean(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_null(&self, context: &GlobalContext) -> bool {
+    pub fn is_null(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsNull(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_undefined(&self, context: &GlobalContext) -> bool {
+    pub fn is_undefined(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsUndefined(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_number(&self, context: &GlobalContext) -> bool {
+    pub fn is_number(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsNumber(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_string(&self, context: &GlobalContext) -> bool {
+    pub fn is_string(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsString(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_object(&self, context: &GlobalContext) -> bool {
+    pub fn is_object(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsObject(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_array(&self, context: &GlobalContext) -> bool {
+    pub fn is_array(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsArray(context.raw, self.raw) != 0 }
     }
 
-    pub fn is_date(&self, context: &GlobalContext) -> bool {
+    pub fn is_date(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueIsDate(context.raw, self.raw) != 0 }
     }
 
-    pub fn to_number(&self, context: &GlobalContext) -> Option<f64> {
+    pub fn to_number(&self, context: &GlobalContextRef) -> Option<f64> {
         let mut exception = ptr::null_mut();
         let result = unsafe { JSValueToNumber(context.raw, self.raw, &mut exception) };
         if exception.is_null() {
@@ -61,11 +65,11 @@ impl Value {
         }
     }
 
-    pub fn to_boolean(&self, context: &GlobalContext) -> bool {
+    pub fn to_boolean(&self, context: &GlobalContextRef) -> bool {
         unsafe { JSValueToBoolean(context.raw, self.raw) != 0}
     }
 
-    pub fn to_string(&self, context: &GlobalContext) -> Option<String> {
+    pub fn to_string(&self, context: &GlobalContextRef) -> Option<String> {
         unsafe {
             let mut exception = ptr::null_mut();
             let jsstring = JSValueToStringCopy(context.raw, self.raw, &mut exception);
@@ -84,33 +88,42 @@ impl Value {
     }
 }
 
-impl FromGlibPtrNone<JSValueRef> for Value {
+impl FromGlibPtrNone<JSValueRef> for ValueRef {
     unsafe fn from_glib_none(ptr: JSValueRef) -> Self {
-        Value {
+        ValueRef {
             raw: ptr,
         }
     }
 }
 
-impl FromGlibPtrFull<JSValueRef> for Value {
+impl FromGlibPtrFull<JSValueRef> for ValueRef {
     unsafe fn from_glib_full(ptr: JSValueRef) -> Self {
-        Value {
+        ValueRef {
             raw: ptr,
         }
     }
 }
 
-impl FromGlibPtrNone<JSGlobalContextRef> for GlobalContext {
+impl FromGlibPtrNone<*mut JSCValue> for Value {
+    unsafe fn from_glib_none(ptr: *mut JSCValue) -> Self {
+        assert!(ptr != ptr::null_mut());
+        Value {
+            raw: *ptr,
+        }
+    }
+}
+
+impl FromGlibPtrNone<JSGlobalContextRef> for GlobalContextRef {
     unsafe fn from_glib_none(ptr: JSGlobalContextRef) -> Self {
-        GlobalContext {
+        GlobalContextRef {
             raw: ptr,
         }
     }
 }
 
-impl FromGlibPtrFull<JSGlobalContextRef> for GlobalContext {
+impl FromGlibPtrFull<JSGlobalContextRef> for GlobalContextRef {
     unsafe fn from_glib_full(ptr: JSGlobalContextRef) -> Self {
-        GlobalContext {
+        GlobalContextRef {
             raw: ptr,
         }
     }