diff --git a/torchvision/datasets/stl10.py b/torchvision/datasets/stl10.py
index 521056b8ae2..32252c55309 100644
--- a/torchvision/datasets/stl10.py
+++ b/torchvision/datasets/stl10.py
@@ -41,9 +41,14 @@ class STL10(CIFAR10):
         ['test_X.bin', '7f263ba9f9e0b06b93213547f721ac82'],
         ['test_y.bin', '36f9794fa4beb8a2c72628de14fa638e']
     ]
+    splits = ('train', 'train+unlabeled', 'unlabeled', 'test')
 
     def __init__(self, root, split='train',
                  transform=None, target_transform=None, download=False):
+        if split not in self.splits:
+            raise ValueError('Split "{}" not found. Valid splits are: {}'.format(
+                split, ', '.join(self.splits),
+            ))
         self.root = os.path.expanduser(root)
         self.transform = transform
         self.target_transform = target_transform