diff --git a/src/lib/data/storage/IntermediateStorage.cpp b/src/lib/data/storage/IntermediateStorage.cpp
index 9f2c1a41..dfb2f4f4 100644
--- a/src/lib/data/storage/IntermediateStorage.cpp
+++ b/src/lib/data/storage/IntermediateStorage.cpp
@@ -323,22 +323,22 @@ void IntermediateStorage::forEachError(std::function<void(const StorageErrorData
 	}
 }
 
-std::vector<StorageNode> IntermediateStorage::getStorageNodes() const
+const std::vector<StorageNode>& IntermediateStorage::getStorageNodes() const
 {
 	return m_nodes;
 }
 
-std::vector<StorageFile> IntermediateStorage::getStorageFiles() const
+const std::vector<StorageFile>& IntermediateStorage::getStorageFiles() const
 {
 	return m_files;
 }
 
-std::vector<StorageSymbol> IntermediateStorage::getStorageSymbols() const
+const std::vector<StorageSymbol>& IntermediateStorage::getStorageSymbols() const
 {
 	return m_symbols;
 }
 
-std::vector<StorageEdge> IntermediateStorage::getStorageEdges() const
+const std::vector<StorageEdge>& IntermediateStorage::getStorageEdges() const
 {
 	return m_edges;
 }
@@ -365,22 +365,22 @@ std::vector<StorageSourceLocation> IntermediateStorage::getStorageSourceLocation
 	return sourceLocations;
 }
 
-std::vector<StorageOccurrence> IntermediateStorage::getStorageOccurrences() const
+const std::vector<StorageOccurrence>& IntermediateStorage::getStorageOccurrences() const
 {
 	return m_occurrences;
 }
 
-std::vector<StorageComponentAccess> IntermediateStorage::getComponentAccesses() const
+const std::vector<StorageComponentAccess>& IntermediateStorage::getComponentAccesses() const
 {
 	return m_componentAccesses;
 }
 
-std::vector<StorageCommentLocationData> IntermediateStorage::getCommentLocations() const
+const std::vector<StorageCommentLocationData>& IntermediateStorage::getCommentLocations() const
 {
 	return m_commentLocations;
 }
 
-std::vector<StorageErrorData> IntermediateStorage::getErrors() const
+const std::vector<StorageErrorData>& IntermediateStorage::getErrors() const
 {
 	return m_errors;
 }
diff --git a/src/lib/data/storage/IntermediateStorage.h b/src/lib/data/storage/IntermediateStorage.h
index f766c1e8..6bf030e5 100644
--- a/src/lib/data/storage/IntermediateStorage.h
+++ b/src/lib/data/storage/IntermediateStorage.h
@@ -56,16 +56,16 @@ public:
 
 	// for conversion to and from 'SharedIntermediateStorage'
 
-	std::vector<StorageNode> getStorageNodes() const;
-	std::vector<StorageFile> getStorageFiles() const;
-	std::vector<StorageSymbol> getStorageSymbols() const;
-	std::vector<StorageEdge> getStorageEdges() const;
+	const std::vector<StorageNode>& getStorageNodes() const;
+	const std::vector<StorageFile>& getStorageFiles() const;
+	const std::vector<StorageSymbol>& getStorageSymbols() const;
+	const std::vector<StorageEdge>& getStorageEdges() const;
 	std::vector<StorageLocalSymbol> getStorageLocalSymbols() const;
 	std::vector<StorageSourceLocation> getStorageSourceLocations() const;
-	std::vector<StorageOccurrence> getStorageOccurrences() const;
-	std::vector<StorageComponentAccess> getComponentAccesses() const;
-	std::vector<StorageCommentLocationData> getCommentLocations() const;
-	std::vector<StorageErrorData> getErrors() const;
+	const std::vector<StorageOccurrence>& getStorageOccurrences() const;
+	const std::vector<StorageComponentAccess>& getComponentAccesses() const;
+	const std::vector<StorageCommentLocationData>& getCommentLocations() const;
+	const std::vector<StorageErrorData>& getErrors() const;
 
 	void setStorageNodes(const std::vector<StorageNode>& storageNodes);
 	void setStorageFiles(const std::vector<StorageFile>& storageFiles);
diff --git a/src/lib/project/Project.cpp b/src/lib/project/Project.cpp
index 8d8e5464..0f920cda 100644
--- a/src/lib/project/Project.cpp
+++ b/src/lib/project/Project.cpp
@@ -508,12 +508,14 @@ void Project::buildIndex(const RefreshInfo& info, std::shared_ptr<DialogView> di
 				)
 			)
 		);
+
 		// add task for injecting the intermediate storages into the persistent storage
 		taskParallelIndexing->addTask(
 			std::make_shared<TaskGroupSequence>()->addChildTasks(
+				// block until there are indexers running
 				std::make_shared<TaskDecoratorRepeat>(TaskDecoratorRepeat::CONDITION_WHILE_SUCCESS, Task::STATE_SUCCESS)->addChildTask(
 					std::make_shared<TaskReturnSuccessWhile<int>>("indexer_count", TaskReturnSuccessWhile<int>::CONDITION_EQUALS, 0)
-					),
+				),
 				std::make_shared<TaskDecoratorRepeat>(TaskDecoratorRepeat::CONDITION_WHILE_SUCCESS, Task::STATE_SUCCESS)->addChildTask(
 					std::make_shared<TaskGroupSequence>()->addChildTasks(
 						// stopping when indexer count is zero, regardless wether there are still storages left to insert.
@@ -527,6 +529,7 @@ void Project::buildIndex(const RefreshInfo& info, std::shared_ptr<DialogView> di
 				)
 			)
 		);
+
 		// add task that notifies the user of what's going on
 		taskSequential->addTask( // we don't need to hide this dialog again, because it's overridden by other dialogs later on.
 			std::make_shared<TaskLambda>([dialogView]() {