diff --git a/.gitignore b/.gitignore
index 23baa97..17ec080 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,5 +21,8 @@ doc/api/
 *.ipr
 *.iws
 
+# VS Code
+.vscode/
+
 # Other files
 test
diff --git a/lib/core.dart b/lib/core.dart
index 6cd2c5e..0db186f 100644
--- a/lib/core.dart
+++ b/lib/core.dart
@@ -75,21 +75,21 @@ abstract class TMDBApiCore {
       {String method: 'GET', _Params params, bool https: false}) async {
     String query = 'api_key=$_apiKey';
 
-    if (params?.needsSession) {
+    if (params?.needsSession ?? false) {
       if (authentication.sessionId == null) {
         throw new StateError(
             "Can't use this method without having a session ID.");
       } else {
         query += "&session_id=${authentication.sessionId}";
       }
-    } else if (params?.needsGuestSession) {
+    } else if (params?.needsGuestSession ?? false) {
       if (authentication.guestSessionId == null) {
         throw new StateError(
             "Can't use this method without having a guest session ID.");
       } else {
         query += "&guest_session_id=${authentication.guestSessionId}";
       }
-    } else if (params?.needsEitherSession) {
+    } else if (params?.needsEitherSession ?? false) {
       if (authentication.sessionId != null) {
         query += "&session_id=${authentication.sessionId}";
       } else if (authentication.guestSessionId != null) {
@@ -108,7 +108,7 @@ abstract class TMDBApiCore {
     //   params.remove('guest_session_id');
     // }
 
-    if (params?.hasElements && ['GET', 'HEAD', 'DELETE'].contains(method)) {
+    if ((params?.hasElements ?? false) && ['GET', 'HEAD', 'DELETE'].contains(method)) {
       query += '&${params.toString()}';
     }
 
@@ -122,56 +122,20 @@ abstract class TMDBApiCore {
     request.headers['Accept'] = 'application/json';
     request.headers['Content-Type'] = 'application/json';
 
-    if (params?.hasElements && ['POST', 'PUT', 'DELETE'].contains(method)) {
+    if ((params?.hasElements ?? false) && ['POST', 'PUT', 'DELETE'].contains(method)) {
       request.body = params?.toJSON();
     }
 
     try {
       String response = await handleRequest(request);
-      return JSON.decode(response);
+      return json.decode(response);
     } catch (e) {
-      // TODO: Handle exceptions
+      rethrow;
     }
   }
 
-  // Future<Map> _query(String endpoint,
-  //     {String method: 'GET',
-  //     Map<String, String> params,
-  //     _Params params2,
-  //     bool https: false}) async {
-  //   List<String> query = [];
-  //   params ??= new Map<String, String>();
-  //   params['api_key'] = _apiKey;
-  //
-  //   params.forEach((String k, dynamic v) {
-  //     query.add('$k=' + Uri.encodeQueryComponent(v.toString()));
-  //   });
-  //
-  //   Uri url = new Uri(
-  //       scheme: _apiUriHTTPS || https ? 'https' : 'http',
-  //       host: _apiUriHost,
-  //       path: '/$_apiUriVersion/$endpoint');
-  //
-  //   if (['GET', 'HEAD', 'DELETE'].contains(method)) {
-  //     url = url.replace(query: query.join('&'));
-  //   }
-  //
-  //   http.Request request = new http.Request(method, url);
-  //
-  //   if (['POST', 'PUT'].contains(method)) {
-  //     request.body = query.join('&');
-  //   }
-  //
-  //   try {
-  //     String response = await handleRequest(request);
-  //     return JSON.decode(response);
-  //   } catch (e) {
-  //     // TODO: Handle exceptions
-  //   }
-  // }
-
   // Abstract method to be implemented either for dart:html or dart:io.
-  Future<String> handleRequest(Request);
+  Future<String> handleRequest(http.Request request);
 
   Future<String> handleResponse(http.Response response) async {
     if (response.statusCode == 429) {
diff --git a/lib/src/groups/authentication.dart b/lib/src/groups/authentication.dart
index 810d6c8..89839e7 100644
--- a/lib/src/groups/authentication.dart
+++ b/lib/src/groups/authentication.dart
@@ -34,7 +34,7 @@ class Authentication {
       return resp['request_token'];
     } else {
       String msg = "Couldn't obtain new token" +
-          (resp?.containsKey('status_message')
+          ((resp?.containsKey('status_message') ?? false)
               ? ': ' + resp['status_message']
               : '');
       throw new Exception(msg);
@@ -63,7 +63,7 @@ class Authentication {
       return resp['request_token'];
     } else {
       String msg = "Couldn't authenticate user '$username'" +
-          (resp?.containsKey('status_message')
+          ((resp?.containsKey('status_message') ?? false)
               ? ': ' + resp['status_message']
               : '');
       throw new Exception(msg);
@@ -85,7 +85,7 @@ class Authentication {
       return resp['session_id'];
     } else {
       String msg = "Couldn't obtain new session ID" +
-          (resp?.containsKey('status_message')
+          ((resp?.containsKey('status_message') ?? false)
               ? ': ' + resp['status_message']
               : '');
       throw new Exception(msg);
@@ -107,7 +107,7 @@ class Authentication {
       return _guestSessionId;
     } else {
       String msg = "Couldn't obtain new guest session ID" +
-          (resp?.containsKey('status_message')
+          ((resp?.containsKey('status_message') ?? false)
               ? ': ' + resp['status_message']
               : '');
       throw new Exception(msg);
diff --git a/lib/src/params.dart b/lib/src/params.dart
index 1cd785f..f2f1d73 100644
--- a/lib/src/params.dart
+++ b/lib/src/params.dart
@@ -19,9 +19,9 @@ class _Params extends Object with MapMixin {
 
   bool get hasElements => _obj.length > 0;
 
-  operator [](String name) => _obj[name];
+  operator [](dynamic name) => _obj[name];
 
-  operator []=(String name, dynamic value) {
+  operator []=(dynamic name, dynamic value) {
     if (value != null) {
       if (value is bool) {
         _obj[name] = value;
@@ -54,6 +54,6 @@ class _Params extends Object with MapMixin {
     return query.join('&');
   }
 
-  String toJSON() => JSON.encode(_obj);
+  String toJSON() => json.encode(_obj);
 
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 52c6c41..86e9096 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -5,10 +5,10 @@ author: Josep Sayol <josep.sayol@gmail.com>
 homepage: https://github.com/jsayol/dart-tmdb
 
 environment:
-  sdk: '>=1.0.0 <2.0.0'
+  sdk: ">=2.0.0 <3.0.0"
 
 dependencies:
-  http: '>=0.11.0 <0.12.0'
+  http: '^0.12.0'
 
 #dev_dependencies:
 #  test: '>=0.12.0 <0.13.0'