diff --git a/gsplat/rendering.py b/gsplat/rendering.py
index 054e73721..702b63bff 100644
--- a/gsplat/rendering.py
+++ b/gsplat/rendering.py
@@ -111,7 +111,7 @@ def rasterization(
 
     Args:
         means: The 3D centers of the Gaussians. [N, 3]
-        quats: The quaternions of the Gaussians. It's not required to be normalized. [N, 4]
+        quats: The quaternions of the Gaussians (wxyz convension). It's not required to be normalized. [N, 4]
         scales: The scales of the Gaussians. [N, 3]
         opacities: The opacities of the Gaussians. [N]
         colors: The colors of the Gaussians. [(C,) N, D] or [(C,) N, K, 3] for SH coefficients.
diff --git a/gsplat/strategy/ops.py b/gsplat/strategy/ops.py
index cbb3705c3..537bc3c9b 100644
--- a/gsplat/strategy/ops.py
+++ b/gsplat/strategy/ops.py
@@ -323,5 +323,5 @@ def op_sigmoid(x, k=100, x0=0.995):
         * (op_sigmoid(1 - opacities)).unsqueeze(-1)
         * scaler
     )
-    noise = torch.bmm(covars, noise.unsqueeze(-1)).squeeze(-1)
+    noise = torch.einsum("bij,bj->bi", covars, noise)
     params["means"].add_(noise)
diff --git a/gsplat/utils.py b/gsplat/utils.py
index 842917400..8a967e352 100644
--- a/gsplat/utils.py
+++ b/gsplat/utils.py
@@ -6,7 +6,7 @@ def normalized_quat_to_rotmat(quat: Tensor) -> Tensor:
     """Convert normalized quaternion to rotation matrix.
 
     Args:
-        quat: Normalized quaternion (..., 4)
+        quat: Normalized quaternion in wxyz convension. (..., 4)
 
     Returns:
         Rotation matrix (..., 3, 3)