diff --git a/dtbTool b/dtbTool
index 2dcdd87..0c14a94 100644
--- a/dtbTool
+++ b/dtbTool
@@ -408,6 +408,16 @@ def write_padding(f, pagesize):
 	if count != pagesize:
 		output.write(b"".join([b'\x00' for x in range(count)]))
 
+def find_dtb(indir):
+	flist = list()
+	for f in os.listdir(indir):
+		ff = os.path.join(indir, f)
+		if os.path.isfile(ff) and ff.endswith('.dtb'):
+			flist.append(ff)
+		elif os.path.isdir(ff):
+			flist.extend(find_dtb(ff))
+	return flist
+
 if __name__ == "__main__":
 	usage = ("""%prog -o <output file> <input DTB directory> [options]""")
 	parser = OptionParser(usage=usage)
@@ -434,10 +444,7 @@ if __name__ == "__main__":
 
 	pagesize = options.pagesize
 	indir = args[0]
-	flist = [os.path.join(indir, f)
-			for f in os.listdir(indir)
-			if os.path.isfile(os.path.join(indir, f)) and
-			   f.endswith('.dtb')]
+	flist = find_dtb(indir)
 
 	records = []
 	for f in flist: