diff --git a/.github/workflows/python_package.yaml b/.github/workflows/python_package.yaml
index 7c0d30ff..a7e21ae5 100644
--- a/.github/workflows/python_package.yaml
+++ b/.github/workflows/python_package.yaml
@@ -21,6 +21,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ["3.10", "3.11", "3.12"]
+        group: [1, 2, 3, 4]
 
     steps:
       - uses: actions/checkout@v4
@@ -33,7 +34,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install pytest pytest-codspeed
+          python -m pip install pytest pytest-codspeed pytest-split pytest-randomly
           python -m pip install .
           # temp pin until 0.5 is on conda
           python -m pip install "jax<0.5.0"
@@ -41,4 +42,16 @@ jobs:
       - name: Test with pytest
         run: |
           git submodule update --init --recursive
-          pytest -v --durations=0
+          pytest -v --durations=0 \
+            -k "not test_fpack" \
+            --randomly-seed=42 \
+            --splits=4 --group=${{ matrix.group }} --splitting-algorithm least_duration
+
+  build-status:
+    needs: build
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: check status
+        run: |
+          echo "Builds all passed!"
diff --git a/jax_galsim/fitswcs.py b/jax_galsim/fitswcs.py
index fdfe6b42..6b85517b 100644
--- a/jax_galsim/fitswcs.py
+++ b/jax_galsim/fitswcs.py
@@ -1008,6 +1008,30 @@ def FitsWCS(
 FitsWCS._opt_params = {"dir": str, "hdu": int, "compression": str, "text_file": bool}
 
 
+@jax.jit
+def _invert_ab_noraise_loop_body(
+    x, y, u, v, ab, dudxcoef, dudycoef, dvdxcoef, dvdycoef
+):
+    # Want Jac^-1 . du
+    # du
+    du = horner2d(x, y, ab[0], triangle=True) - u
+    dv = horner2d(x, y, ab[1], triangle=True) - v
+    # J
+    dudx = horner2d(x, y, dudxcoef, triangle=True)
+    dudy = horner2d(x, y, dudycoef, triangle=True)
+    dvdx = horner2d(x, y, dvdxcoef, triangle=True)
+    dvdy = horner2d(x, y, dvdycoef, triangle=True)
+    # J^-1 . du
+    det = dudx * dvdy - dudy * dvdx
+    dx = -(du * dvdy - dv * dudy) / det
+    dy = -(-du * dvdx + dv * dudx) / det
+
+    x += dx
+    y += dy
+
+    return x, y, dx, dy
+
+
 @jax.jit
 def _invert_ab_noraise(u, v, ab, abp=None):
     # get guess from abp if we have it
@@ -1029,22 +1053,9 @@ def _invert_ab_noraise(u, v, ab, abp=None):
     dvdycoef = (jnp.arange(nab) * ab[1])[:-1, 1:]
 
     for _ in range(10):
-        # Want Jac^-1 . du
-        # du
-        du = horner2d(x, y, ab[0], triangle=True) - u
-        dv = horner2d(x, y, ab[1], triangle=True) - v
-        # J
-        dudx = horner2d(x, y, dudxcoef, triangle=True)
-        dudy = horner2d(x, y, dudycoef, triangle=True)
-        dvdx = horner2d(x, y, dvdxcoef, triangle=True)
-        dvdy = horner2d(x, y, dvdycoef, triangle=True)
-        # J^-1 . du
-        det = dudx * dvdy - dudy * dvdx
-        dx = -(du * dvdy - dv * dudy) / det
-        dy = -(-du * dvdx + dv * dudx) / det
-
-        x += dx
-        y += dy
+        x, y, dx, dy = _invert_ab_noraise_loop_body(
+            x, y, u, v, ab, dudxcoef, dudycoef, dvdxcoef, dvdycoef
+        )
 
     x, y = jax.lax.cond(
         jnp.maximum(jnp.max(jnp.abs(dx)), jnp.max(jnp.abs(dy))) > 2e-12,
diff --git a/tests/galsim_tests_config.yaml b/tests/galsim_tests_config.yaml
index 7557c2be..0efc2e1b 100644
--- a/tests/galsim_tests_config.yaml
+++ b/tests/galsim_tests_config.yaml
@@ -61,7 +61,6 @@ allowed_failures:
   - "module 'jax_galsim.utilities' has no attribute 'dol_to_lod'"
   - "module 'jax_galsim.utilities' has no attribute 'nCr'"
   - "module 'jax_galsim' has no attribute 'LookupTable'"
-  - "module 'jax_galsim.bessel' has no attribute 'j0'"
   - "module 'jax_galsim.bessel' has no attribute 'j1'"
   - "module 'jax_galsim.bessel' has no attribute 'jn'"
   - "module 'jax_galsim.bessel' has no attribute 'jv'"
@@ -69,7 +68,6 @@ allowed_failures:
   - "module 'jax_galsim.bessel' has no attribute 'yv'"
   - "module 'jax_galsim.bessel' has no attribute 'iv'"
   - "module 'jax_galsim.bessel' has no attribute 'kn'"
-  - "module 'jax_galsim.bessel' has no attribute 'kv'"
   - "module 'jax_galsim.bessel' has no attribute 'j0_root'"
   - "module 'jax_galsim.bessel' has no attribute 'gammainc'"
   - "module 'jax_galsim.bessel' has no attribute 'sinc'"
@@ -145,6 +143,6 @@ allowed_failures:
   - "Sensor/photon_ops not yet implemented in drawImage for method != 'phot'"
   - "module 'jax_galsim' has no attribute 'SiliconSensor'"
   - "module 'jax_galsim' has no attribute 'set_omp_threads'"
-  - "module 'jax_galsim' has no attribute 'Spergel'"
   - "module 'jax_galsim' has no attribute 'LookupTable2D'"
   - "module 'jax_galsim' has no attribute 'zernike'"
+  - "Invalid TFORM4: 1PE(7)"  # see https://github.com/astropy/astropy/issues/15477