diff --git a/arangod/Indexes/PrimaryIndex.cpp b/arangod/Indexes/PrimaryIndex.cpp
index 33d2c2a5f7..33aaf53378 100644
--- a/arangod/Indexes/PrimaryIndex.cpp
+++ b/arangod/Indexes/PrimaryIndex.cpp
@@ -110,10 +110,7 @@ size_t PrimaryIndex::size () const {
 }
 
 size_t PrimaryIndex::memory () const {
-  return static_cast<size_t>(
-      _primaryIndex->size() * sizeof(TRI_doc_mptr_t*) +
-      _primaryIndex->memoryUsage()
-  );
+  return _primaryIndex->memoryUsage();
 }
 
 ////////////////////////////////////////////////////////////////////////////////