diff --git a/timm/data/readers/reader_tfds.py b/timm/data/readers/reader_tfds.py
index 7ccbf908..a327df7b 100644
--- a/timm/data/readers/reader_tfds.py
+++ b/timm/data/readers/reader_tfds.py
@@ -38,9 +38,9 @@ from .reader import Reader
 from .shared_count import SharedCount
 
 
-MAX_TP_SIZE = os.environ.get('TFDS_TP_SIZE', 8)  # maximum TF threadpool size, for jpeg decodes and queuing activities
-SHUFFLE_SIZE = os.environ.get('TFDS_SHUFFLE_SIZE', 8192)  # samples to shuffle in DS queue
-PREFETCH_SIZE = os.environ.get('TFDS_PREFETCH_SIZE', 2048)  # samples to prefetch
+MAX_TP_SIZE = int(os.environ.get('TFDS_TP_SIZE', 8))  # maximum TF threadpool size, for jpeg decodes and queuing activities
+SHUFFLE_SIZE = int(os.environ.get('TFDS_SHUFFLE_SIZE', 8192))  # samples to shuffle in DS queue
+PREFETCH_SIZE = int(os.environ.get('TFDS_PREFETCH_SIZE', 2048))  # samples to prefetch
 
 
 def even_split_indices(split, n, num_samples):
diff --git a/timm/data/readers/reader_wds.py b/timm/data/readers/reader_wds.py
index afc9030b..36890eed 100644
--- a/timm/data/readers/reader_wds.py
+++ b/timm/data/readers/reader_wds.py
@@ -34,7 +34,7 @@ from .shared_count import SharedCount
 
 _logger = logging.getLogger(__name__)
 
-SHUFFLE_SIZE = os.environ.get('WDS_SHUFFLE_SIZE', 8192)
+SHUFFLE_SIZE = int(os.environ.get('WDS_SHUFFLE_SIZE', 8192))
 
 
 def _load_info(root, basename='info'):