diff --git a/src/kyupy/__init__.py b/src/kyupy/__init__.py
index 89ee51a..2ed27f8 100644
--- a/src/kyupy/__init__.py
+++ b/src/kyupy/__init__.py
@@ -81,7 +81,6 @@ def hr_time(seconds):
 
 
 def batchrange(nitems, maxsize):
-    assert nitems >= maxsize
     for offset in range(0, nitems, maxsize):
         yield offset, min(nitems-offset, maxsize)
 
diff --git a/src/kyupy/logic.py b/src/kyupy/logic.py
index b0a82a3..368d1b7 100644
--- a/src/kyupy/logic.py
+++ b/src/kyupy/logic.py
@@ -115,6 +115,7 @@ def mv_str(mva, delim='\n'):
     """Renders a given multi-valued array into a string.
     """
     sa = np.choose(mva, np.array([*'0X-1PRFN'], dtype=np.unicode_))
+    if not hasattr(mva, 'ndim') or mva.ndim == 0: return sa
     if mva.ndim == 1: return ''.join(sa)
     return delim.join([''.join(c) for c in sa.swapaxes(-1,-2)])