diff --git a/Cocoa/Document.m b/Cocoa/Document.m
index 15fc1aa1..1cfef34b 100644
--- a/Cocoa/Document.m
+++ b/Cocoa/Document.m
@@ -675,4 +675,9 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
     return &gb;
 }
 
++ (BOOL)canConcurrentlyReadDocumentsOfType:(NSString *)typeName
+{
+    return YES;
+}
+
 @end
\ No newline at end of file