diff --git a/packages/graphrag/graphrag/index/operations/embed_text/embed_text.py b/packages/graphrag/graphrag/index/operations/embed_text/embed_text.py
index 59424272d6..b1f5db8056 100644
--- a/packages/graphrag/graphrag/index/operations/embed_text/embed_text.py
+++ b/packages/graphrag/graphrag/index/operations/embed_text/embed_text.py
@@ -133,6 +133,13 @@ async def _flush_embedding_buffer(
             )
         )
 
+    if documents:
+        dims = {len(d.vector) for d in documents}
+        if len(dims) > 1:
+            msg = f"Inconsistent embedding dimensions: {dims}. Check that your embedding model returns consistent vector sizes."
+            callbacks.error(msg)
+            raise ValueError(msg)
+
     vector_store.load_documents(documents)
 
     if skipped > 0:
diff --git a/packages/graphrag/pyproject.toml b/packages/graphrag/pyproject.toml
index f9fa8b5373..7d1bc0cb58 100644
--- a/packages/graphrag/pyproject.toml
+++ b/packages/graphrag/pyproject.toml
@@ -46,7 +46,7 @@ dependencies = [
     "graspologic-native~=1.2",
     "json-repair~=0.30",
     "networkx~=3.4",
-    "nltk~=3.9",
+    "nltk>=3.9.3",
     "numpy~=2.1",
     "pandas~=2.3",
     "pyarrow~=22.0",