diff --git a/bitten/bitten.py b/bitten/bitten.py
index 37c5e38..9210824 100644
--- a/bitten/bitten.py
+++ b/bitten/bitten.py
@@ -171,6 +171,28 @@ def _penalize3(constraints, *x, tol=1e-5, scale=1e10, growth=3.0):
     return scale * (penalty - nominal + 1.0)
 
 
+def _penalize4(constraints, *x, tol=1e-5, scale=1e9):
+    # updated from upstream (v2022.23)
+    # NOTE: i've reduced `scale` by a factor of ten
+    #       out of concern for numeric precision.
+    #       also, i've removed the growth keyword, since it very likely
+    #       needs to coincide with the order of the polynomial (always 3).
+    penalties = _flatten(cons(*x) for cons in constraints)
+    n_con = len(penalties)
+    growth = 3.0 ** (1.0 / n_con)  # "ps"
+    increment = n_con**-0.5  # "pnsi"
+    # coeff = increment**3.0  # "pnm"
+    penalty, nominal = 0.0, 0.0  # "pns", "pnsm"
+    for p in penalties:
+        p = max(p - tol, 0.0)
+        v = p  # * coeff  # 2022.25 drops the coeff
+        v2 = v * v
+        poly = v + v2 + v * v2
+        penalty = penalty * growth + increment + poly
+        nominal = nominal * growth + increment
+    return scale * (penalty - nominal + 1.0)
+
+
 def penalize(x, constraints, tol=1e-5, *, scale=1e10, growth=4.0):
     # DEPRECATED
     return _penalize(constraints, x, tol=tol, scale=scale, growth=growth)
@@ -294,9 +316,10 @@ class Constrain(Objective):
 
     @version.setter
     def version(self, version):
-        assert 1 <= version <= 3, version
+        penalizers = [_penalize, _penalize2, _penalize3, _penalize4]
+        assert 1 <= version <= len(penalizers), version
         self._version = version - 1
-        self._penalize = [_penalize, _penalize2, _penalize3][self._version]
+        self._penalize = penalizers[self._version]
 
     def penalize(self, *args):
         return self._penalize(self.constraints, *args, tol=self.tol)