diff --git a/klippy/extras/resonance_tester.py b/klippy/extras/resonance_tester.py
index df557f93..55fa5583 100644
--- a/klippy/extras/resonance_tester.py
+++ b/klippy/extras/resonance_tester.py
@@ -178,7 +178,10 @@ class ResonanceTester:
                             "%s-axis accelerometer measured no data" % (
                                 chip_axis,))
                 new_data = helper.process_accelerometer_data(chip_values)
-                data = data.join(new_data) if data else new_data
+                if data is None:
+                    data = new_data
+                else:
+                    data.add_data(new_data)
         if csv_output:
             csv_name = self.save_calibration_data('resonances', name_suffix,
                                                   helper, axis, data)
@@ -251,7 +254,7 @@ class ResonanceTester:
                     if calibration_data[axis] is None:
                         calibration_data[axis] = new_data
                     else:
-                        calibration_data[axis].join(new_data)
+                        calibration_data[axis].add_data(new_data)
 
         configfile = self.printer.lookup_object('configfile')
 
diff --git a/klippy/extras/shaper_calibrate.py b/klippy/extras/shaper_calibrate.py
index 71e5e489..3c6065de 100644
--- a/klippy/extras/shaper_calibrate.py
+++ b/klippy/extras/shaper_calibrate.py
@@ -142,7 +142,7 @@ class CalibrationData:
         self._psd_map = {'x': self.psd_x, 'y': self.psd_y, 'z': self.psd_z,
                          'all': self.psd_sum}
         self.data_sets = 1
-    def join(self, other):
+    def add_data(self, other):
         np = self.numpy
         joined_data_sets = self.data_sets + other.data_sets
         for psd, other_psd in zip(self._psd_list, other._psd_list):
diff --git a/scripts/calibrate_shaper.py b/scripts/calibrate_shaper.py
index bd2d4308..5bbc9eea 100755
--- a/scripts/calibrate_shaper.py
+++ b/scripts/calibrate_shaper.py
@@ -45,12 +45,12 @@ def calibrate_shaper(datas, csv_output, max_smoothing):
     if isinstance(datas[0], CalibrationData):
         calibration_data = datas[0]
         for data in datas[1:]:
-            calibration_data.join(data)
+            calibration_data.add_data(data)
     else:
         # Process accelerometer data
         calibration_data = helper.process_accelerometer_data(datas[0])
         for data in datas[1:]:
-            calibration_data.join(helper.process_accelerometer_data(data))
+            calibration_data.add_data(helper.process_accelerometer_data(data))
         calibration_data.normalize_to_frequencies()
     shaper, all_shapers = helper.find_best_shaper(
             calibration_data, max_smoothing, print)
diff --git a/scripts/graph_accelerometer.py b/scripts/graph_accelerometer.py
index 93dd413b..472530d3 100755
--- a/scripts/graph_accelerometer.py
+++ b/scripts/graph_accelerometer.py
@@ -82,7 +82,7 @@ def calc_specgram(data, axis):
 def plot_frequency(datas, lognames, max_freq):
     calibration_data = calc_freq_response(datas[0], max_freq)
     for data in datas[1:]:
-        calibration_data.join(calc_freq_response(data, max_freq))
+        calibration_data.add_data(calc_freq_response(data, max_freq))
     freqs = calibration_data.freq_bins
     psd = calibration_data.psd_sum[freqs <= max_freq]
     px = calibration_data.psd_x[freqs <= max_freq]
@@ -158,7 +158,7 @@ def write_frequency_response(datas, output):
     helper = ShaperCalibrate(printer=None)
     calibration_data = helper.process_accelerometer_data(datas[0])
     for data in datas[1:]:
-        calibration_data.join(helper.process_accelerometer_data(data))
+        calibration_data.add_data(helper.process_accelerometer_data(data))
     helper.save_calibration_data(output, calibration_data)
 
 def write_specgram(psd, freq_bins, time, output):