diff --git a/.github/workflows/test-langchain.yml b/.github/workflows/test-langchain.yml
index b8f0237c..87e41a23 100644
--- a/.github/workflows/test-langchain.yml
+++ b/.github/workflows/test-langchain.yml
@@ -42,6 +42,9 @@ jobs:
           - 4200:4200
           - 5432:5432
 
+    env:
+      OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+
     steps:
 
       - name: Acquire sources
diff --git a/framework/langchain/pyproject.toml b/framework/langchain/pyproject.toml
index b9e54d6b..264cb82c 100644
--- a/framework/langchain/pyproject.toml
+++ b/framework/langchain/pyproject.toml
@@ -22,6 +22,7 @@ markers = [
 # pytest-notebook settings
 nb_test_files = true
 nb_coverage = true
+nb_exec_allow_errors = true
 nb_diff_replace = [
     # Compensate output of `crash`.
     '"/cells/*/outputs/*/text" "\(\d.\d+ sec\)" "(0.000 sec)"',
diff --git a/framework/langchain/test.py b/framework/langchain/test.py
index b6f537e4..39f41de8 100644
--- a/framework/langchain/test.py
+++ b/framework/langchain/test.py
@@ -46,6 +46,17 @@ def str_list(things):
     return map(str, things)
 
 
+@pytest.fixture(scope="session", autouse=True)
+def nltk_init():
+    """
+    Initialize nltk upfront, so that it does not run stray output into Jupyter Notebooks.
+    """
+    download_items = ["averaged_perceptron_tagger", "punkt"]
+    import nltk
+    for item in download_items:
+        nltk.download(item)
+
+
 @pytest.fixture(scope="function", autouse=True)
 def db_init():
     """
diff --git a/framework/langchain/vector_search.ipynb b/framework/langchain/vector_search.ipynb
index 00921d3f..f4f787b2 100644
--- a/framework/langchain/vector_search.ipynb
+++ b/framework/langchain/vector_search.ipynb
@@ -239,6 +239,11 @@
     },
     "pycharm": {
      "is_executing": true
+    },
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
     }
    },
    "outputs": [],
@@ -277,6 +282,11 @@
     "ExecuteTime": {
      "end_time": "2023-09-09T08:05:13.532334Z",
      "start_time": "2023-09-09T08:05:13.523191Z"
+    },
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
     }
    },
    "outputs": [],
@@ -329,6 +339,11 @@
     "ExecuteTime": {
      "end_time": "2023-09-09T08:05:27.478580Z",
      "start_time": "2023-09-09T08:05:27.470138Z"
+    },
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
     }
    }
   },
@@ -371,7 +386,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+   },
    "outputs": [],
    "source": [
     "store.add_documents([Document(page_content=\"foo\")])"
@@ -389,7 +410,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+   },
    "outputs": [],
    "source": [
     "docs_with_score[0]"
@@ -398,7 +425,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+   },
    "outputs": [],
    "source": [
     "docs_with_score[1]"
@@ -417,7 +450,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+},
    "outputs": [],
    "source": [
     "db = CrateDBVectorSearch.from_documents(\n",
@@ -441,7 +480,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+   },
    "outputs": [],
    "source": [
     "docs_with_score[0]"
@@ -466,7 +511,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {},
+   "metadata": {
+    "nbreg": {
+     "diff_ignore": [
+      "/outputs"
+     ]
+    }
+   },
    "outputs": [],
    "source": [
     "print(retriever)"