Parameter contexts are non-final

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3dad00c..68d3899 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.1.3
+
+- Parameters contexts are non final
+
 ## 0.1.2
 
 - Parameters have contexts associated with them

diff --git a/lib/param.dart b/lib/param.dart
index f296c9d..a2e7e17 100644
--- a/lib/param.dart
+++ b/lib/param.dart

@@ -6,11 +6,9 @@
 
 class Param extends _EquationMember {
   final Variable variable;
-  final dynamic context;
+  dynamic context;
 
-  Param([double value = 0.0])
-      : variable = new Variable(value),
-        context = null {
+  Param([double value = 0.0]) : variable = new Variable(value) {
     variable._owner = this;
   }
 

diff --git a/pubspec.yaml b/pubspec.yaml
index 5f42495..922c9f7 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml

@@ -1,5 +1,5 @@
 name: cassowary
-version: 0.1.2
+version: 0.1.3
 description: Cassowary Constraint Solving Toolkit
 author: Chromium Authors <sky-dev@googlegroups.com>
 homepage: https://github.com/domokit/cassowary

diff --git a/test/cassowary_test.dart b/test/cassowary_test.dart
index 1ea67e1..0eaf130 100644
--- a/test/cassowary_test.dart
+++ b/test/cassowary_test.dart

@@ -579,4 +579,10 @@
     expect(mid.value, 50.0);
     expect(right.value, 90.0);
   });
+
+  test('param_context_non_final', () {
+    var p = new Param.withContext("a");
+    p.context = "b";
+    expect(p.context, "b");
+  });
 }