diff --git a/prody/atomic/select.py b/prody/atomic/select.py
index 445dc44dd..a58ad749e 100644
--- a/prody/atomic/select.py
+++ b/prody/atomic/select.py
@@ -1403,6 +1403,7 @@ def _and2(self, sel, loc, tokens, subset=None):
                 elif token in UNARY:
                     unary.append([])
                     append = unary[-1].append
+                    wasdata = False
 
                     if token == 'not':
                         append((token,))