diff --git a/src/pygama/evt/modules/larveto.py b/src/pygama/evt/modules/larveto.py
index 28b827c83..f26ae3b8e 100644
--- a/src/pygama/evt/modules/larveto.py
+++ b/src/pygama/evt/modules/larveto.py
@@ -70,8 +70,16 @@ def l200_test_stat(relative_t0, amp, ts_bkg_prob, rc_density):
     n_pe_tot = np.where(n_pe_tot == 0, np.nan, n_pe_tot)
 
     # calculate the test statistic term related to the time distribution
-    transform_function = transform_wrapper(ts_bkg_prob)
-    ts_time = -ak.sum(ak.transform(transform_function, relative_t0, amp), axis=-1)
+    ts_time = -ak.sum(
+        ak.transform(
+            lambda layouts, **kwargs: _ak_l200_test_stat_time_term(
+                layouts, ts_bkg_prob, **kwargs
+            ),
+            relative_t0,
+            amp,
+        ),
+        axis=-1,
+    )
     # calculate the amplitude contribution
     ts_amp = [l200_rc_amp_logpdf(n, rc_density) for n in n_pe_tot]
 
@@ -81,14 +89,6 @@ def l200_test_stat(relative_t0, amp, ts_bkg_prob, rc_density):
     return t_stat
 
 
-# need this to pass ts_bkg_prob parameter with ak.transform()
-def transform_wrapper(ts_bkg_prob):
-    def _transform(layouts, **kwargs):
-        return _ak_l200_test_stat_time_term(layouts, ts_bkg_prob=ts_bkg_prob)
-
-    return _transform
-
-
 # need to define this function and use it with ak.transform() because scipy
 # routines are not NumPy universal functions
 def _ak_l200_test_stat_time_term(layouts, ts_bkg_prob, **kwargs):