diff --git a/src/core/unified_resources_provider.cpp b/src/core/unified_resources_provider.cpp
index 1028d09fd..643acaea6 100644
--- a/src/core/unified_resources_provider.cpp
+++ b/src/core/unified_resources_provider.cpp
@@ -86,6 +86,9 @@ void UnifiedResourcesProvider::remergeItems( void )
 	PointerHashMap itemsSeen;
 
 	ResourcesDB::ItemList & items = database()->items();
+
+	itemsSeen.reserve( items.size() );
+
 	for( ResourcesDB::ItemList::Iterator it = items.begin();
 						it != items.end(); ++it )
 	{