diff --git a/tools/releasetools/sparse_img.py b/tools/releasetools/sparse_img.py
index 78f3057..c9e7e76 100644
--- a/tools/releasetools/sparse_img.py
+++ b/tools/releasetools/sparse_img.py
@@ -201,12 +201,8 @@
           nonzero_blocks.append(b)
           nonzero_blocks.append(b+1)
 
-    assert zero_blocks or nonzero_blocks
-
-    if zero_blocks:
-      out["__ZERO"] = rangelib.RangeSet(data=zero_blocks)
-    if nonzero_blocks:
-      out["__NONZERO"] = rangelib.RangeSet(data=nonzero_blocks)
+    out["__ZERO"] = RangeSet(data=zero_blocks)
+    out["__NONZERO"] = RangeSet(data=nonzero_blocks)
 
   def ResetFileMap(self):
     """Throw away the file map and treat the entire image as