diff --git a/nifty5/__init__.py b/nifty5/__init__.py
index 7e4fd2f28dfe8b6625c7d2c3c954f772a8a39089..06e55763400db9cd4fabe4c51001d651cdb77e9e 100644
--- a/nifty5/__init__.py
+++ b/nifty5/__init__.py
@@ -74,7 +74,8 @@ from .minimization.metric_gaussian_kl import MetricGaussianKL
 from .sugar import *
 from .plot import Plot
 
-from .library.smooth_linear_amplitude import SLAmplitude, LinearSLAmplitude, CepstrumOperator
+from .library.smooth_linear_amplitude import (
+    SLAmplitude, LinearSLAmplitude, CepstrumOperator)
 from .library.inverse_gamma_operator import InverseGammaOperator
 from .library.los_response import LOSResponse
 from .library.dynamic_operator import (dynamic_operator,
diff --git a/nifty5/library/smooth_linear_amplitude.py b/nifty5/library/smooth_linear_amplitude.py
index 97c3c52c1df2b82174f2a38c42b9c06b4502bd9d..f9c7187e826f1486d8d9810e1c007f6898e8b94b 100644
--- a/nifty5/library/smooth_linear_amplitude.py
+++ b/nifty5/library/smooth_linear_amplitude.py
@@ -111,6 +111,7 @@ def CepstrumOperator(target, a, k0):
 
     return sym @ qht @ makeOp(cepstrum.sqrt())
 
+
 def SLAmplitude(*, target, n_pix, a, k0, sm, sv, im, iv, keys=['tau', 'phi']):
     '''Operator for parametrizing smooth amplitudes (square roots of power
     spectra).
@@ -168,13 +169,15 @@ def SLAmplitude(*, target, n_pix, a, k0, sm, sv, im, iv, keys=['tau', 'phi']):
         which returns on its target a power spectrum which consists out of a
         smooth and a linear part.
     '''
-    return LinearSLAmplitude(target=target, n_pix=n_pix, a=a, k0=k0, sm=sm, sv=sv, im=im, iv=iv, keys=keys).exp()
+    return LinearSLAmplitude(target=target, n_pix=n_pix, a=a, k0=k0, sm=sm,
+                             sv=sv, im=im, iv=iv, keys=keys).exp()
 
 
-def LinearSLAmplitude(*, target, n_pix, a, k0, sm, sv, im, iv, keys=['tau', 'phi']):
-    '''LinearOperator for parametrizing smooth log-amplitudes (square roots of power
-    spectra).
-    
+def LinearSLAmplitude(*, target, n_pix, a, k0, sm, sv, im, iv,
+                      keys=['tau', 'phi']):
+    '''LinearOperator for parametrizing smooth log-amplitudes (square roots of
+    power spectra).
+
     Logarithm of SLAmplitude
     See documentation of SLAmplitude for more details
     '''