diff --git a/skimage/io/collection.py b/skimage/io/collection.py
index a8a890f4..aab7cb86 100644
--- a/skimage/io/collection.py
+++ b/skimage/io/collection.py
@@ -163,10 +163,11 @@ class ImageCollection(object):
             for pattern in load_pattern:
                 self._files.extend(glob(pattern))
             self._files = sorted(self._files, key=alphanumeric_key)
+            self._numframes = self._find_images()
         else:
             self._files = load_pattern
-
-        self._numframes = self._find_images()
+            self._numframes = len(self._files)
+            self._frame_index = None
 
         if conserve_memory:
             memory_slots = 1