diff --git a/src/scikits/bootstrap/bootstrap.py b/src/scikits/bootstrap/bootstrap.py
index 9cd854d..cb3f02c 100644
--- a/src/scikits/bootstrap/bootstrap.py
+++ b/src/scikits/bootstrap/bootstrap.py
@@ -66,36 +66,49 @@
 
 def _ncdf_py(x: float) -> float:
     return 0.5 * (1 + cast(float, erf(x / s2)))
-ncdf = np.vectorize(_ncdf_py, [float])
 
 
+ncdf = np.vectorize(_ncdf_py, [float])
+
+# fmt: off
 def nppf(p):
     p = np.asarray(p)
     out = np.empty_like(p, dtype=float)
     ix1 = (p < 0.02425) & (p > 0)
     oix1 = np.sqrt(-2 * np.log(p[ix1]))
     out[ix1] = (
-            (((((-7.784894002430293e-03 * oix1 - 3.223964580411365e-01) * oix1 - 2.400758277161838e00) * oix1 - 2.549732539343734e00) * oix1 + 4.374664141464968e00) * oix1 + 2.938163982698783e00)
-            / ((((7.784695709041462e-03 * oix1 + 3.224671290700398e-01) * oix1 + 2.445134137142996e00) * oix1 + 3.754408661907416e00) * oix1 + 1)
+            (((((-7.784894002430293e-03 * oix1 - 3.223964580411365e-01) * oix1 
+                - 2.400758277161838e00) * oix1 - 2.549732539343734e00) * oix1 
+                + 4.374664141464968e00) * oix1 + 2.938163982698783e00)
+            / ((((7.784695709041462e-03 * oix1 + 3.224671290700398e-01) * oix1 
+                 + 2.445134137142996e00) * oix1 + 3.754408661907416e00) * oix1 + 1)
         )
 
     ix2 = (0.02425 <= p) & (p <= 0.97575)
     oix2 = (p[ix2] - 0.5)
     sq = oix2 * oix2
     out[ix2] = (
-            (((((-3.969683028665376e01 * sq + 2.209460984245205e02) * sq - 2.759285104469687e02) * sq + 1.383577518672690e02) * sq - 3.066479806614716e01) * sq + 2.506628277459239e00) * oix2
-        ) / (((((-5.447609879822406e01 * sq + 1.615858368580409e02) * sq - 1.556989798598866e02) * sq + 6.680131188771972e01) * sq - 1.328068155288572e01) * sq + 1)
+            (((((-3.969683028665376e01 * sq + 2.209460984245205e02) * sq 
+                - 2.759285104469687e02) * sq + 1.383577518672690e02) * sq 
+                - 3.066479806614716e01) * sq + 2.506628277459239e00) * oix2
+        ) / (((((-5.447609879822406e01 * sq + 1.615858368580409e02) * sq 
+                - 1.556989798598866e02) * sq + 6.680131188771972e01) * sq 
+                - 1.328068155288572e01) * sq + 1)
 
     ix3 = (p > 0.97575) & (p < 1)
     oix3 = np.sqrt(-2 * np.log(1 - p[ix3]))
     out[ix3] = -(
-            (((((-7.784894002430293e-03 * oix3 - 3.223964580411365e-01) * oix3 - 2.400758277161838e00) * oix3 - 2.549732539343734e00) * oix3 + 4.374664141464968e00) * oix3 + 2.938163982698783e00)
-            / ((((7.784695709041462e-03 * oix3 + 3.224671290700398e-01) * oix3 + 2.445134137142996e00) * oix3 + 3.754408661907416e00) * oix3 + 1)
+            (((((-7.784894002430293e-03 * oix3 - 3.223964580411365e-01) * oix3 
+                - 2.400758277161838e00) * oix3 - 2.549732539343734e00) * oix3 
+                + 4.374664141464968e00) * oix3 + 2.938163982698783e00)
+            / ((((7.784695709041462e-03 * oix3 + 3.224671290700398e-01) * oix3 
+                 + 2.445134137142996e00) * oix3 + 3.754408661907416e00) * oix3 + 1)
         )
     out[p == 0] = -np.inf
     out[p == 1] = np.inf
     
     return out
+# fmt: on
 
 __version__ = "1.1.0"
 
diff --git a/tox.ini b/tox.ini
index cd30754..1bd2cd4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,6 @@ commands =
     pytest --cov --cov-report=xml --cov-report=term-missing {posargs:-vv}
 deps =
     numpy
-    pyerf
     pytest
     pytest-cov
     !pypy3-pandas: pandas