diff --git a/pyrelacs/dataio/circbuffer.py b/pyrelacs/dataio/circbuffer.py
index 03993a2..629fea4 100644
--- a/pyrelacs/dataio/circbuffer.py
+++ b/pyrelacs/dataio/circbuffer.py
@@ -55,7 +55,7 @@ class CircBuffer:
             return self._buffer[channel, : self._index[channel]]
 
     def has_value(self, index, channel):
-        if index < 0 and self.is_full(channel):
+        if index <= 0 and self.is_full(channel):
             return True
         elif index < 0 and not self.is_full(channel):
             return False
@@ -73,6 +73,8 @@ class CircBuffer:
         if index == self.write_index(channel) and self._totalcount[channel] == 0:
             return False
 
+        return True
+
     def valid_range(self, channel: int = 0) -> Tuple[int, int]:
         """
         Return the start index that are valid within the buffer