diff --git a/neo/rawio/plexonrawio.py b/neo/rawio/plexonrawio.py
index 5e759f995..0f713fcb0 100644
--- a/neo/rawio/plexonrawio.py
+++ b/neo/rawio/plexonrawio.py
@@ -694,7 +694,7 @@ def read_as_dict(fid, dtype, offset=None):
 DataBlockHeader = [
     ("Type", "uint16"),
     ("UpperByteOf5ByteTimestamp", "uint16"),
-    ("TimeStamp", "int32"),
+    ("TimeStamp", "uint32"),
     ("Channel", "uint16"),
     ("Unit", "uint16"),
     ("NumberOfWaveforms", "uint16"),