diff --git a/pandas/tools/util.py b/pandas/tools/util.py
index fec56328c1721..b50bf9dc448bc 100644
--- a/pandas/tools/util.py
+++ b/pandas/tools/util.py
@@ -205,7 +205,7 @@ def to_numeric(arg, errors='raise', downcast=None):
 
         if downcast in ('integer', 'signed'):
             typecodes = np.typecodes['Integer']
-        elif downcast == 'unsigned' and np.min(values) > 0:
+        elif downcast == 'unsigned' and np.min(values) >= 0:
             typecodes = np.typecodes['UnsignedInteger']
         elif downcast == 'float':
             typecodes = np.typecodes['Float']