diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index fbb87b9..f7555cf 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -501,7 +501,7 @@
       ParmVarDecl *Param = (*P);
       Expr *rhs = new (Context) DeclRefExpr(Param,Param->getType(),
                                             SourceLocation());
-      ExprResult Res = BuildBinOp(S, SourceLocation(), 
+      ExprResult Res = BuildBinOp(S, lhs->getLocEnd(), 
                                   BO_Assign, lhs, rhs);
       PIDecl->setSetterCXXAssignment(Res.takeAs<Expr>());
     }
diff --git a/test/SemaObjCXX/property-synthesis-error.mm b/test/SemaObjCXX/property-synthesis-error.mm
new file mode 100644
index 0000000..59e17b2
--- /dev/null
+++ b/test/SemaObjCXX/property-synthesis-error.mm
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// rdar: //8550657
+
+@interface NSArray @end
+
+@interface NSMutableArray : NSArray @end
+
+@interface MyClass
+{
+  NSMutableArray * _array;
+}
+
+@property (readonly) NSArray * array;
+
+@end
+
+@interface MyClass ()
+
+@property (readwrite) NSMutableArray * array;
+
+@end
+
+@implementation MyClass
+
+@synthesize array=_array; // expected-error {{assigning to 'NSMutableArray *' from incompatible type 'NSArray *'}}
+
+@end
+
+int main(void)
+{
+  return 0;
+}