diff --git a/straxen/plugins/merged_s2s/merged_s2s.py b/straxen/plugins/merged_s2s/merged_s2s.py
index e01a567d9..484d13a1a 100644
--- a/straxen/plugins/merged_s2s/merged_s2s.py
+++ b/straxen/plugins/merged_s2s/merged_s2s.py
@@ -70,7 +70,16 @@ def setup(self):
         self.to_pe = self.gain_model
 
     def infer_dtype(self):
-        return strax.unpack_dtype(self.deps["peaklets"].dtype_for("peaklets"))
+        peaklet_classification_dtype = self.deps["peaklet_classification"].dtype_for(
+            "peaklet_classification"
+        )
+        peaklets_dtype = self.deps["peaklets"].dtype_for("peaklets")
+        # The merged dtype is argument position dependent!
+        # It must be first classification then peaklet
+        # Otherwise strax will raise an error
+        # when checking for the returned dtype!
+        merged_s2s_dtype = strax.merged_dtype((peaklet_classification_dtype, peaklets_dtype))
+        return merged_s2s_dtype
 
     def get_window_size(self):
         return self.merged_s2s_get_window_size_factor * (
@@ -132,7 +141,7 @@ def compute(self, peaklets, lone_hits):
         lh = strax.sort_by_time(lh)
 
         # If sum_waveform_top_array is false, don't digitize the top array
-        n_top_pmts_if_digitize_top = self.n_top_pmts if self.sum_waveform_top_array else -1
+        n_top_pmts_if_digitize_top = self.n_top_pmts if "data_top" in self.dtype.names else -1
         strax.add_lone_hits(merged_s2s, lh, self.to_pe, n_top_channels=n_top_pmts_if_digitize_top)
 
         strax.compute_widths(merged_s2s)
diff --git a/straxen/plugins/peaks/peaks.py b/straxen/plugins/peaks/peaks.py
index 18226abcb..9e5d1e815 100644
--- a/straxen/plugins/peaks/peaks.py
+++ b/straxen/plugins/peaks/peaks.py
@@ -65,4 +65,7 @@ def compute(self, peaklets, merged_s2s):
             assert np.all(
                 peaks["time"][to_check][1:] >= strax.endtime(peaks)[to_check][:-1]
             ), "Peaks not disjoint"
-        return peaks
+
+        result = np.zeros(len(peaks), self.dtype)
+        strax.copy_to_buffer(peaks, result, "_copy_requested_peak_fields")
+        return result