diff --git a/diffdrr/pose.py b/diffdrr/pose.py
index 0d67b6ff9..cd63145e1 100644
--- a/diffdrr/pose.py
+++ b/diffdrr/pose.py
@@ -637,6 +637,7 @@ def axis_angle_to_quaternion(axis_angle: torch.Tensor) -> torch.Tensor:
     """
     angles = torch.norm(axis_angle, p=2, dim=-1, keepdim=True)
     half_angles = angles * 0.5
+    eps = 1e-6
     small_angles = angles.abs() < eps
     large = torch.sin(half_angles) / angles
     small = 0.5 - (angles * angles) / 48
diff --git a/notebooks/api/06_pose.ipynb b/notebooks/api/06_pose.ipynb
index ab9afd213..3f06e0d58 100644
--- a/notebooks/api/06_pose.ipynb
+++ b/notebooks/api/06_pose.ipynb
@@ -837,6 +837,7 @@
     "    \"\"\"\n",
     "    angles = torch.norm(axis_angle, p=2, dim=-1, keepdim=True)\n",
     "    half_angles = angles * 0.5\n",
+    "    eps = 1e-6\n",
     "    small_angles = angles.abs() < eps\n",
     "    large = torch.sin(half_angles) / angles\n",
     "    small = 0.5 - (angles * angles) / 48\n",