diff --git a/packages/langium/src/lsp/default-lsp-module.ts b/packages/langium/src/lsp/default-lsp-module.ts
index 31cec433b..cbc093d8a 100644
--- a/packages/langium/src/lsp/default-lsp-module.ts
+++ b/packages/langium/src/lsp/default-lsp-module.ts
@@ -97,7 +97,7 @@ export function createDefaultSharedLSPModule(context: DefaultSharedModuleContext
         },
         workspace: {
             TextDocuments: () => new NormalizedTextDocuments(TextDocument),
-            NotebookDocuments: () => new NormalizedNotebookDocuments(TextDocument)
+            NotebookDocuments: (services) => new NormalizedNotebookDocuments(services.workspace.TextDocuments)
         }
     };
 }
diff --git a/packages/langium/src/lsp/normalized-text-documents.ts b/packages/langium/src/lsp/normalized-text-documents.ts
index 2003d6518..6ccd03b38 100644
--- a/packages/langium/src/lsp/normalized-text-documents.ts
+++ b/packages/langium/src/lsp/normalized-text-documents.ts
@@ -325,8 +325,8 @@ export class NormalizedNotebookDocuments<T extends { uri: DocumentUri }> impleme
         return this.notebookDocuments.get(UriUtils.normalize(uri));
     }
 
-    getNotebookCell(uri: DocumentUri): NotebookCell | undefined {
-        const value = this.notebookCellMap.get(uri);
+    getNotebookCell(uri: string | URI): NotebookCell | undefined {
+        const value = this.notebookCellMap.get(UriUtils.normalize(uri));
         return value && value[0];
     }