diff --git a/base/include/hidl/MQDescriptor.h b/base/include/hidl/MQDescriptor.h
index 0429444..38ac325 100644
--- a/base/include/hidl/MQDescriptor.h
+++ b/base/include/hidl/MQDescriptor.h
@@ -181,7 +181,11 @@
 
 template<typename T, MQFlavor flavor>
 size_t MQDescriptor<T, flavor>::getSize() const {
-    return static_cast<size_t>(mGrantors[details::DATAPTRPOS].extent);
+    if (mGrantors.size() > details::DATAPTRPOS) {
+        return static_cast<size_t>(mGrantors[details::DATAPTRPOS].extent);
+    } else {
+        return 0;
+    }
 }
 
 template<typename T, MQFlavor flavor>