diff --git a/syncropatch_export/trace.py b/syncropatch_export/trace.py
index 2737fb5..edd70d9 100644
--- a/syncropatch_export/trace.py
+++ b/syncropatch_export/trace.py
@@ -1,6 +1,5 @@
 import json
 import os
-import string
 
 import numpy as np
 
@@ -53,20 +52,28 @@ def __init__(self, filepath, json_file: str):
         self.MeasurementLayout = TraceHeader['MeasurementLayout']
         self.FileInformation = TraceHeader['FileInformation']
 
-        # Create (hardcoded) list-of-list of well names:
+        # Create list-of-list of well names, e.g. for SyncroPatch:
         #  [['A01', 'B01', ..., 'P01'],
         #   ['A02', 'B02', ..., 'P02'],
         #   ...
         #   ['A24', 'B24', ..., 'P24']]
         # So a list of 24 lists with 16 entries each
-        #
+        # "rows" here is columns in the above matrix!
+        self.WP_nRows = TraceHeader['Chiplayout']['WP_nRows']
+        self.WP_nCols = TraceHeader['Chiplayout']['WP_nCols']
+        if self.WP_nRows > 26:
+            raise NotImplementedError(  # pragma: no cover
+                'Unsupported chip layout (more than 26 rows)')
+        if self.WP_nCols > 99:
+            raise NotImplementedError(  # pragma: no cover
+                'Unsupported chip layout (more than 99 columns)')
+        abc = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
         self.WELL_ID = np.array([
-            [lab + str(i).zfill(2) for lab in string.ascii_uppercase[:16]]
-            for i in range(1, 25)])
+            [f'{abc[i]}{j:>02}' for i in range(self.WP_nRows)]
+            for j in range(1, self.WP_nCols + 1)
+        ])
 
         self.NofSweeps = self.MeasurementLayout['NofSweeps']
-        self.WP_nRows = TraceHeader['Chiplayout']['WP_nRows']
-        self.WP_nCols = TraceHeader['Chiplayout']['WP_nCols']
         self.nCols = self.MeasurementLayout['nCols']
         self.NofSamples = self.MeasurementLayout['NofSamples']
         self.Leakdata = self.MeasurementLayout['Leakdata']
diff --git a/tests/test_trace_class.py b/tests/test_trace_class.py
index 1d2de6c..b29190d 100755
--- a/tests/test_trace_class.py
+++ b/tests/test_trace_class.py
@@ -90,17 +90,24 @@ def test_get_QC(self):
         self.assertGreater(len(QC_values), 0)
 
     def test_get_traces(self):
+
+        # Check well ids
+        self.assertEqual(self.trace.WELL_ID[3, 2], 'C04')
+        self.assertEqual(len(self.trace.WELL_ID), 24)
+        self.assertEqual(len(self.trace.WELL_ID[0]), 16)
+
+        # Check voltage and time
         v = self.trace.get_voltage()
         ts = self.trace.get_times()
-        all_traces = self.trace.get_all_traces(leakcorrect=True)
-        all_traces = self.trace.get_all_traces()
-        # TODO: Check the output, numerically, by comparing a few points
-
         self.assertTrue(np.all(np.isfinite(v)))
         self.assertTrue(np.all(np.isfinite(ts)))
 
+        # Check traces
+        all_traces = self.trace.get_all_traces(leakcorrect=True)
+        all_traces = self.trace.get_all_traces()
         for well, trace in all_traces.items():
             self.assertTrue(np.all(np.isfinite(trace)))
+        # TODO: Check the output, numerically, by comparing a few points
 
         # Test complex sweep selection
         a = self.trace.get_trace_sweeps([-1, -2])