diff --git a/README.md b/README.md
index 41e3a9f7..707fe201 100644
--- a/README.md
+++ b/README.md
@@ -38,10 +38,6 @@ The recommended way is to install Annif from
     source annif-venv/bin/activate
     pip install annif
 
-You will also need NLTK data files:
-
-    python -m nltk.downloader punkt_tab
-
 Start up the application:
 
     annif
@@ -113,10 +109,6 @@ Enter the virtual environment:
 
     poetry shell
 
-You will also need NLTK data files:
-
-    python -m nltk.downloader punkt_tab
-
 Start up the application:
 
     annif
diff --git a/annif/analyzer/analyzer.py b/annif/analyzer/analyzer.py
index 25bdb6b5..129b882a 100644
--- a/annif/analyzer/analyzer.py
+++ b/annif/analyzer/analyzer.py
@@ -6,7 +6,12 @@
 import functools
 import unicodedata
 
+import annif
+
+logger = annif.logger
+
 _KEY_TOKEN_MIN_LENGTH = "token_min_length"
+_NLTK_TOKENIZER_DATA = "punkt_tab"
 
 
 class Analyzer(metaclass=abc.ABCMeta):
@@ -21,6 +26,21 @@ def __init__(self, **kwargs) -> None:
         if _KEY_TOKEN_MIN_LENGTH in kwargs:
             self.token_min_length = int(kwargs[_KEY_TOKEN_MIN_LENGTH])
 
+        import nltk.data
+
+        try:
+            nltk.data.find("tokenizers/" + _NLTK_TOKENIZER_DATA)
+        except LookupError as err:
+            logger.debug(str(err))
+            if _NLTK_TOKENIZER_DATA in str(err):
+                logger.warning(
+                    f'NLTK datapackage "{_NLTK_TOKENIZER_DATA}" not found, '
+                    "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."""
         import nltk.tokenize
diff --git a/tests/test_analyzer.py b/tests/test_analyzer.py
index ecddfbb3..ff4b7079 100644
--- a/tests/test_analyzer.py
+++ b/tests/test_analyzer.py
@@ -1,5 +1,7 @@
 """Unit tests for analyzers in Annif"""
 
+from unittest import mock
+
 import pytest
 
 import annif.analyzer
@@ -15,6 +17,15 @@ def test_get_analyzer_badspec():
         annif.analyzer.get_analyzer("()")
 
 
+@mock.patch("nltk.data.find", side_effect=LookupError("Resource punkt_tab not found"))
+@mock.patch("nltk.download")
+def test_nltk_data_missing(download, find):
+    annif.analyzer.get_analyzer("snowball(english)")
+    assert find.called
+    assert download.called
+    assert download.call_args == mock.call("punkt_tab")
+
+
 def test_english_analyzer_normalize_word():
     analyzer = annif.analyzer.get_analyzer("snowball(english)")
     assert analyzer._normalize_word("running") == "run"