diff --git a/ndbioimage/readers/cziread.py b/ndbioimage/readers/cziread.py
index d349ea2..a1771c9 100644
--- a/ndbioimage/readers/cziread.py
+++ b/ndbioimage/readers/cziread.py
@@ -178,6 +178,8 @@ class Reader(AbstractReader, ABC):
         ti = self.reader.axes.index("T") if "T" in self.reader.axes else None
         yi = self.reader.axes.index("Y") if "Y" in self.reader.axes else None
         xi = self.reader.axes.index("X") if "X" in self.reader.axes else None
+        if si is None and self.series > 0:
+            raise FileNotFoundError(f"Series {self.series} not found in {self.path}.")
 
         for directory_entry in self.reader.filtered_subblock_directory:
             idx = self.get_index(directory_entry, self.reader.start)
@@ -194,7 +196,7 @@ class Reader(AbstractReader, ABC):
             if self.series < len(b):
                 by, bx = b[self.series]
             else:
-                raise FileNotFoundError(self.path / f"Pos{self.series}")
+                raise FileNotFoundError(f"Series {self.series} not found in {self.path}.")
             for directory_entry in self.reader.filtered_subblock_directory:
                 idx = self.get_index(directory_entry, self.reader.start)
                 if bx[0] <= idx[xi][0] <= bx[1] and by[0] <= idx[yi][0] <= by[1]:
diff --git a/pyproject.toml b/pyproject.toml
index ff08820..1a10a19 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "ndbioimage"
-version = "2026.3.4"
+version = "2026.3.5"
 description = "Bio image reading, metadata and some affine registration."
 authors = [
     { name = "W. Pomp", email = "w.pomp@nki.nl" }