diff --git a/large_image/tilesource/base.py b/large_image/tilesource/base.py
index 4170a4062..4d68eaa0f 100644
--- a/large_image/tilesource/base.py
+++ b/large_image/tilesource/base.py
@@ -1591,7 +1591,7 @@ def getInternalMetadata(self, **kwargs):
         """
         return None
 
-    def _xyzInRange(self, x, y, z):
+    def _xyzInRange(self, x, y, z, frame=None, numFrames=None):
         """
         Check if a tile at x, y, z is in range based on self.levels,
         self.tileWidth, self.tileHeight, self.sizeX, and self.sizeY,  Raise an
@@ -1606,6 +1606,9 @@ def _xyzInRange(self, x, y, z):
         offsety = y * self.tileHeight * scale
         if not (0 <= offsety < self.sizeY):
             raise exceptions.TileSourceException('y is outside layer')
+        if frame is not None and numFrames is not None:
+            if frame < 0 or frame >= numFrames:
+                raise exceptions.TileSourceException('Frame does not exist')
 
     @methodcache()
     def getTile(self, x, y, z, pilImageAllowed=False, numpyAllowed=False,
diff --git a/sources/nd2/large_image_source_nd2/__init__.py b/sources/nd2/large_image_source_nd2/__init__.py
index 9be14ad6b..3be76ed10 100644
--- a/sources/nd2/large_image_source_nd2/__init__.py
+++ b/sources/nd2/large_image_source_nd2/__init__.py
@@ -302,16 +302,13 @@ def getInternalMetadata(self, **kwargs):
 
     @methodcache()
     def getTile(self, x, y, z, pilImageAllowed=False, numpyAllowed=False, **kwargs):
-        self._xyzInRange(x, y, z)
+        frame = int(kwargs.get('frame') or 0)
+        self._xyzInRange(x, y, z, frame, len(self._nd2))
         step = int(2 ** (self.levels - 1 - z))
         x0 = x * step * self.tileWidth
         x1 = min((x + 1) * step * self.tileWidth, self.sizeX)
         y0 = y * step * self.tileHeight
         y1 = min((y + 1) * step * self.tileHeight, self.sizeY)
-        frame = kwargs.get('frame')
-        frame = int(frame) if frame else 0
-        if frame < 0 or frame >= len(self._nd2):
-            raise TileSourceException('Frame does not exist')
         with self._tileLock:
             if frame in self._recentFrames:
                 tileframe = self._recentFrames[frame]
diff --git a/sources/ometiff/large_image_source_ometiff/__init__.py b/sources/ometiff/large_image_source_ometiff/__init__.py
index 6b4403ee2..f8237103c 100644
--- a/sources/ometiff/large_image_source_ometiff/__init__.py
+++ b/sources/ometiff/large_image_source_ometiff/__init__.py
@@ -84,6 +84,7 @@ def __init__(self, path, **kwargs):
 
         :param path: a filesystem path for the tile source.
         """
+        # Note this is the super of the parent class, not of this class.
         super(TiffFileTileSource, self).__init__(path, **kwargs)
 
         largeImagePath = self._getLargeImagePath()
diff --git a/sources/openslide/large_image_source_openslide/__init__.py b/sources/openslide/large_image_source_openslide/__init__.py
index 3ecd4f551..c2cf57ed3 100644
--- a/sources/openslide/large_image_source_openslide/__init__.py
+++ b/sources/openslide/large_image_source_openslide/__init__.py
@@ -271,10 +271,7 @@ def getInternalMetadata(self, **kwargs):
     @methodcache()
     def getTile(self, x, y, z, pilImageAllowed=False, numpyAllowed=False, **kwargs):
         self._xyzInRange(x, y, z)
-        try:
-            svslevel = self._svslevels[z]
-        except IndexError:
-            raise TileSourceException('z layer does not exist')
+        svslevel = self._svslevels[z]
         # When we read a region from the SVS, we have to ask for it in the
         # SVS level 0 coordinate system.  Our x and y is in tile space at the
         # specifed z level, so the offset in SVS level 0 coordinates has to be