diff --git a/README.md b/README.md
index 8f52ad7fb1834c7a0182a18823124b18cd5df2a8..e0068c6269a89fce2df9123aeaaef4b25fe18e94 100644
--- a/README.md
+++ b/README.md
@@ -71,6 +71,9 @@ Depending on the extra options the duration varies:
 | `solve_integral_exactly`, `include_Ga`, `ignore_symmetries` | 122.82 |
 
 ## Versions
+version 14.15:
+* set Tk=1 in second order truncation
+
 version 14.x:
 * based on versions 8 and 13
 * implements the RG for the system with and without unitary transformation (version 8 and 13)
diff --git a/kondo.py b/kondo.py
index f8a35c234bbe51186148a3b16bbced7756a5ecaa..69e8663d6e9a18d5b407e42ce080a83c9b576080 100644
--- a/kondo.py
+++ b/kondo.py
@@ -138,7 +138,7 @@ def gen_init_matrix(nmax, *fourier_coef, resonant_dc_shift=0, resolution=5000):
 
 def solveTV0_scalar_order2(
         d,
-        tk = 0.32633176486110027,
+        tk = 1, # TODO: prior to version 14.15 this was 0.32633176486110027
         rtol = 1e-8,
         atol = 1e-10,
         full_output = False,
diff --git a/settings.py b/settings.py
index 34fc36d8909f2cc0ec646bb62e3ae7181cb6010f..81f8e9d9c4e5fab475e391f061a9d069bda2ecdb 100644
--- a/settings.py
+++ b/settings.py
@@ -86,7 +86,7 @@ class GlobalFlags:
         BASEPATH = os.path.abspath("data"),
         DB_CONNECTION_STRING = "sqlite:///" + os.path.join(os.path.abspath("data"), "frtrg.sqlite"),
         FILENAME = "frtrg-04.h5",
-        VERSION = (14, 14, -1, -1),
+        VERSION = (14, 15, -1, -1),
         MIN_VERSION = (14, 0),
         LOG_TIME = 10, # in s
         ENFORCE_SYMMETRIC = 0,