diff --git a/TODO b/TODO
index f030cee..deafa05 100644
--- a/TODO
+++ b/TODO
@@ -5,7 +5,6 @@
 [ target: 0.1.0 ]
   Misc
     - Class module is becoming too large; refactor
-    - Disallow member redeclaration in definition
     - Permit binding on class methods
     - Move tests to directly test propobj
       - Was never done after refactoring. It's tested as a consequence of being
diff --git a/lib/class.js b/lib/class.js
index d352f0a..a8a1e08 100644
--- a/lib/class.js
+++ b/lib/class.js
@@ -444,6 +444,7 @@ var extend = ( function( extending )
             properties = {},
             prop_init  = member_builder.initMembers(),
             members    = member_builder.initMembers( prototype ),
+            defs       = {},
 
             abstract_methods =
                 util.clone( getMeta( base ).abstractMethods )
@@ -480,6 +481,19 @@ var extend = ( function( extending )
                         "__initProps is a reserved method"
                     );
                 }
+
+                // if a member was defined multiple times in the same class
+                // declaration, throw an error
+                if ( hasOwn.call( defs, name ) )
+                {
+                    throw Error(
+                        "Cannot redefine method '" + name + "' in same declaration"
+                    );
+                }
+
+                // keep track of the definitions (only during class declaration)
+                // to catch duplicates
+                defs[ name ] = 1;
             },
 
             property: function( name, value, keywords )
diff --git a/test/test-class-extend.js b/test/test-class-extend.js
index f60df03..29aa3fd 100644
--- a/test/test-class-extend.js
+++ b/test/test-class-extend.js
@@ -311,3 +311,40 @@ for ( var i = 0; i < class_count; i++ )
     );
 } )();
 
+
+/**
+ * In ease.js's initial design, keywords were not included. This meant that
+ * duplicate member definitions were not possible - it'd throw a parse error.
+ * However, with keywords, it is now possible to redeclare a member with the
+ * same name in the same class definition. Since this doesn't make much sense,
+ * we must disallow it.
+ */
+( function testCannotProvideDuplicateMemberDefintions()
+{
+    assert.throws( function()
+    {
+        Class(
+        {
+            // declare as protected first so that we won't get a visibility
+            // de-escalation error with the below re-definition
+            'protected foo': '',
+
+            // should fail; redefinition
+            'public foo': '',
+        } );
+    }, Error, "Cannot redeclare property in same class definition" );
+
+    assert.throws( function()
+    {
+        Class(
+        {
+            // declare as protected first so that we won't get a visibility
+            // de-escalation error with the below re-definition
+            'protected foo': function() {},
+
+            // should fail; redefinition
+            'public foo': function() {},
+        } );
+    }, Error, "Cannot redeclare method in same class definition" );
+} )();
+