diff --git a/script/device/Image.py b/script/device/Image.py
index aa4affc..6c5c470 100644
--- a/script/device/Image.py
+++ b/script/device/Image.py
@@ -81,35 +81,42 @@ def is_locked(filepath):
         print "%s not found." % filepath
     return locked
 
-def wait_for_files(filepaths):
+def wait_for_files(filepaths, timeout = None):
     """Checks if the files are ready.
 
     For a file to be ready it must exist and can be opened in append
     mode.
     """
-    wait_time = 5
+    wait_time = 0.01
     for filepath in filepaths:
         filepath = os.path.abspath(filepath)
         # If the file doesn't exist, wait wait_time seconds and try again
         # until it's found.
         while not os.path.exists(filepath):
-            print "%s hasn't arrived. Waiting %s seconds." % \
-                  (filepath, wait_time)
+            if (timeout is not None) and  (time.time() -start  > timeout):
+                raise Exception(filepath + " hasn't arrived in time")
             time.sleep(wait_time)
+            
         # If the file exists but locked, wait wait_time seconds and check
         # again until it's no longer locked by another process.
         while is_locked(filepath):
-            print "%s is currently in use. Waiting %s seconds." % \
-                  (filepath, wait_time)
+            if (timeout is not None) and  (time.time() -start  > timeout):
+                raise Exception(filepath + " hasn't arrived in time")
             time.sleep(wait_time)            
 
 
-def wait_for_file_size(filepath, size):
+def wait_for_file_size(filepath, size, timeout = None):
+    """Wait for a file to exist, and reach a given size.
+    """
+
     wait_time = 0.01
     filepath = os.path.abspath(filepath)
+    start = time.time()
     # If the file doesn't exist, wait wait_time seconds and try again
     # until it's found.
     while not os.path.exists(filepath) or size > os.path.getsize(filepath):
+        if (timeout is not None) and  (time.time() -start  > timeout):
+                raise Exception(filepath + " hasn't arrived in time")
         time.sleep(wait_time)