diff --git a/sensirion_driver_adapters/rx_tx_data.py b/sensirion_driver_adapters/rx_tx_data.py
index 2f731c5..6a82a27 100644
--- a/sensirion_driver_adapters/rx_tx_data.py
+++ b/sensirion_driver_adapters/rx_tx_data.py
@@ -162,9 +162,10 @@ def unpack_dynamic_sized(self, data):
                 elif is_string:  # a string
                     val = val[0].decode()
                 unpacked.append(val)
+                data_pos += field_len
             else:
                 descriptor = f"{byte_order_specifier} {descriptor}"
                 unpacked.extend(struct.unpack_from(descriptor, data, data_pos))
-            data_pos += elem_size
+                data_pos += elem_size
             match = self.field_match.match(self._descriptor, descriptor_pos)
         return tuple(unpacked)
diff --git a/tests/test_pack_unpack.py b/tests/test_pack_unpack.py
index 1905cd9..a917b19 100644
--- a/tests/test_pack_unpack.py
+++ b/tests/test_pack_unpack.py
@@ -52,7 +52,10 @@ def test_unpack(rx: RxData, data):
 
 @pytest.mark.parametrize("rx, data", [(RxData(">HH"), (0xABCD, 1234)),
                                       (RxData(">HH8B"), (0xABCD, 1234, (1, 2, 3, 4, 5, 6, 7, 8))),
-                                      (RxData(">I16s"), (0xABCD, 'hello world'))])
+                                      (RxData(">I16s"), (0xABCD, 'hello world')),
+                                      (RxData(">I8BHHH"), (0x0803028D,
+                                                           (0x32, 0x32, 0x32, 0x38, 0x42, 0x44, 0x00, 0x00),
+                                                           0x0C10, 0x1121, 0x0054))])
 def test_dynamic_unpack(rx: RxData, data):
     to_pack = []
     for d in data: