diff --git a/poky/scripts/lib/wic/filemap.py b/poky/scripts/lib/wic/filemap.py
index 244c07a..a3919fb 100644
--- a/poky/scripts/lib/wic/filemap.py
+++ b/poky/scripts/lib/wic/filemap.py
@@ -32,7 +32,10 @@
     """
     # Get the block size of the host file-system for the image file by calling
     # the FIGETBSZ ioctl (number 2).
-    binary_data = fcntl.ioctl(file_obj, 2, struct.pack('I', 0))
+    try:
+        binary_data = fcntl.ioctl(file_obj, 2, struct.pack('I', 0))
+    except OSError:
+        raise IOError("Unable to determine block size")
     bsize = struct.unpack('I', binary_data)[0]
     if not bsize:
         import os