diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index b4aee7c..7f6d8c3 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -276,11 +276,18 @@
       L->AddedObjCPropertyInClassExtension(PDecl, /*OrigProp=*/0, CDecl);
     return PDecl;
   }
-  if (PIDecl->getType().getCanonicalType() 
-      != PDecl->getType().getCanonicalType()) {
-    Diag(AtLoc, 
-         diag::err_type_mismatch_continuation_class) << PDecl->getType();
-    Diag(PIDecl->getLocation(), diag::note_property_declare);
+  if (!Context.hasSameType(PIDecl->getType(), PDecl->getType())) {
+    bool IncompatibleObjC = false;
+    QualType ConvertedType;
+    if (!isa<ObjCObjectPointerType>(PIDecl->getType()) ||
+        !isa<ObjCObjectPointerType>(PDecl->getType()) ||
+        (!isObjCPointerConversion(PDecl->getType(), PIDecl->getType(), 
+                                  ConvertedType, IncompatibleObjC))
+        || IncompatibleObjC) {
+      Diag(AtLoc, 
+          diag::err_type_mismatch_continuation_class) << PDecl->getType();
+      Diag(PIDecl->getLocation(), diag::note_property_declare);
+    }
   }
     
   // The property 'PIDecl's readonly attribute will be over-ridden
diff --git a/test/SemaObjC/narrow-property-type-in-cont-class.m b/test/SemaObjC/narrow-property-type-in-cont-class.m
new file mode 100644
index 0000000..3ba848f
--- /dev/null
+++ b/test/SemaObjC/narrow-property-type-in-cont-class.m
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -x objective-c -fsyntax-only -verify %s
+// RUN: %clang_cc1 -x objective-c++ -fsyntax-only -verify %s
+// rdar://10790488
+
+@interface NSArray @end
+
+@interface NSMutableArray : NSArray
+@end
+
+@interface GKTurnBasedMatchMakerKVO
+@property(nonatomic,readonly,retain) NSArray* outline;
+@property(nonatomic,readonly,retain) NSMutableArray* err_outline; // expected-note {{property declared here}}
+@end
+
+@interface GKTurnBasedMatchMakerKVO ()
+@property(nonatomic,readwrite,retain) NSMutableArray* outline;
+@property(nonatomic,readwrite,retain) NSArray* err_outline; // expected-error {{type of property 'NSArray *' in continuation class does not match property type in primary class}}
+@end
+