diff --git a/annif/analyzer/analyzer.py b/annif/analyzer/analyzer.py
index 4b647c18..129b882a 100644
--- a/annif/analyzer/analyzer.py
+++ b/annif/analyzer/analyzer.py
@@ -38,6 +38,8 @@ def __init__(self, **kwargs) -> None:
                     "downloading it now."
                 )
                 nltk.download(_NLTK_TOKENIZER_DATA)
+            else:
+                raise
 
     def tokenize_sentences(self, text: str) -> list[str]:
         """Tokenize a piece of text (e.g. a document) into sentences."""