diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 9c1e4a9..4a2f0b4 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -84,8 +84,13 @@
                        VDecl->getName(), DefaultArg->getSourceRange());
     }
 
-    // FIXME: when Clang has support for member functions, "this"
-    // will also need to be diagnosed.
+    // C++ [dcl.fct.default]p8:
+    //   The keyword this shall not be used in a default argument of a
+    //   member function.
+    // Note: this requirement is already diagnosed by
+    // Sema::ActOnCXXThis, because the use of "this" inside a default
+    // argument doesn't occur inside the body of a non-static member
+    // function.
 
     return false;
   }
diff --git a/test/SemaCXX/default2.cpp b/test/SemaCXX/default2.cpp
index d3e999c..89eb467 100644
--- a/test/SemaCXX/default2.cpp
+++ b/test/SemaCXX/default2.cpp
@@ -36,3 +36,7 @@
   void (*f2)(int = 17)  // {expected-error {{default arguments can only be specified}}}
     = (void (*)(int = 42))f; // {expected-error {{default arguments can only be specified}}}
 }
+
+class X {
+  void f(X* x = this); // expected-error{{invalid use of 'this' outside of a nonstatic member function}}
+};