diff --git a/src/felupe/constitution/jax/_helpers.py b/src/felupe/constitution/jax/_helpers.py
index bd362070..fba57c7c 100644
--- a/src/felupe/constitution/jax/_helpers.py
+++ b/src/felupe/constitution/jax/_helpers.py
@@ -95,7 +95,6 @@ def vmap2(fun, in_axes=[0, 0], out_axes=[0, 0], methods=[jax.vmap, jax.vmap], **
 
 
 def as_total_lagrange(fun):
-
     @wraps(fun)
     def evaluate(F, *args, **kwargs):
         i, j = jnp.triu_indices(3)
diff --git a/src/felupe/constitution/jax/_hyperelastic.py b/src/felupe/constitution/jax/_hyperelastic.py
index f18d83f9..8460d8cc 100644
--- a/src/felupe/constitution/jax/_hyperelastic.py
+++ b/src/felupe/constitution/jax/_hyperelastic.py
@@ -146,7 +146,6 @@ def viscoelastic(C, Cin, mu, eta, dtime):
     """
 
     def __init__(self, fun, nstatevars=0, jit=True, parallel=False, **kwargs):
-
         has_aux = nstatevars > 0
         self.fun = as_total_lagrange(fun)
 
diff --git a/src/felupe/constitution/jax/_material.py b/src/felupe/constitution/jax/_material.py
index 44317b3e..722979db 100644
--- a/src/felupe/constitution/jax/_material.py
+++ b/src/felupe/constitution/jax/_material.py
@@ -160,7 +160,6 @@ def viscoelastic(F, Cin, mu, eta, dtime):
     def __init__(
         self, fun, nstatevars=0, jit=True, parallel=False, jacobian=None, **kwargs
     ):
-
         has_aux = nstatevars > 0
         self.fun = fun
 
diff --git a/src/felupe/constitution/jax/models/hyperelastic/_mooney_rivlin.py b/src/felupe/constitution/jax/models/hyperelastic/_mooney_rivlin.py
index fd04eddc..9f28837c 100644
--- a/src/felupe/constitution/jax/models/hyperelastic/_mooney_rivlin.py
+++ b/src/felupe/constitution/jax/models/hyperelastic/_mooney_rivlin.py
@@ -25,7 +25,6 @@
 
 @wraps(mooney_rivlin_docstring)
 def mooney_rivlin(C, C10, C01):
-
     J3 = det(C) ** (-1 / 3)
     I1 = J3 * trace(C)
     I2 = (I1**2 - J3**2 * trace(C @ C)) / 2
diff --git a/src/felupe/constitution/jax/models/hyperelastic/_third_order_deformation.py b/src/felupe/constitution/jax/models/hyperelastic/_third_order_deformation.py
index 429ce33f..b1fe2ce7 100644
--- a/src/felupe/constitution/jax/models/hyperelastic/_third_order_deformation.py
+++ b/src/felupe/constitution/jax/models/hyperelastic/_third_order_deformation.py
@@ -25,7 +25,6 @@
 
 @wraps(tod_docstring)
 def third_order_deformation(C, C10, C01, C11, C20, C30):
-
     J3 = det(C) ** (-1 / 3)
     I1 = J3 * trace(C)
     I2 = (I1**2 - J3**2 * trace(C @ C)) / 2
diff --git a/src/felupe/constitution/jax/models/hyperelastic/_yeoh.py b/src/felupe/constitution/jax/models/hyperelastic/_yeoh.py
index 6ac3236a..010bec7f 100644
--- a/src/felupe/constitution/jax/models/hyperelastic/_yeoh.py
+++ b/src/felupe/constitution/jax/models/hyperelastic/_yeoh.py
@@ -25,6 +25,5 @@
 
 @wraps(yeoh_docstring)
 def yeoh(C, C10, C20, C30):
-
     I1 = det(C) ** (-1 / 3) * trace(C)
     return C10 * (I1 - 3) + C20 * (I1 - 3) ** 2 + C30 * (I1 - 3) ** 3
diff --git a/src/felupe/constitution/jax/models/lagrange/_morph.py b/src/felupe/constitution/jax/models/lagrange/_morph.py
index 47c1b213..cf7d8c3c 100644
--- a/src/felupe/constitution/jax/models/lagrange/_morph.py
+++ b/src/felupe/constitution/jax/models/lagrange/_morph.py
@@ -28,7 +28,6 @@
 @wraps(morph_docstring)
 @total_lagrange
 def morph(F, statevars, p):
-
     # right Cauchy-Green deformation tensor
     C = F.T @ F
 
diff --git a/src/felupe/constitution/jax/models/lagrange/_morph_uniaxial.py b/src/felupe/constitution/jax/models/lagrange/_morph_uniaxial.py
index b168539c..dd176f39 100644
--- a/src/felupe/constitution/jax/models/lagrange/_morph_uniaxial.py
+++ b/src/felupe/constitution/jax/models/lagrange/_morph_uniaxial.py
@@ -25,7 +25,6 @@
 
 @wraps(morph_ux)
 def morph_uniaxial(λ, statevars, p, ε=1e-6):
-
     CTSn = statevars[:21]
     λn = 1 + statevars[21:42]
     SA1n = statevars[42:63]
diff --git a/tests/test_constitution_jax.py b/tests/test_constitution_jax.py
index 32c066a7..8cf6dc06 100644
--- a/tests/test_constitution_jax.py
+++ b/tests/test_constitution_jax.py
@@ -78,7 +78,6 @@ def test_hyperelastic_jax():
 
 
 def test_hyperelastic_jax_statevars():
-
     def W(C, statevars, C10, K):
         I3 = jnp.linalg.det(C)
         J = jnp.sqrt(I3)
@@ -99,7 +98,6 @@ def W(C, statevars, C10, K):
 
 
 def test_material_jax():
-
     def dWdF(F, C10, K):
         J = jnp.linalg.det(F)
         C = F.T @ F
@@ -124,7 +122,6 @@ def dWdF(F, C10, K):
 
 
 def test_material_jax_statevars():
-
     def dWdF(F, statevars, C10, K):
         J = jnp.linalg.det(F)
         C = F.T @ F
@@ -149,7 +146,6 @@ def dWdF(F, statevars, C10, K):
 
 
 def test_material_included_jax_statevars():
-
     for fun, nstatevars in zip(
         [
             mat.models.lagrange.morph,