diff --git a/pytorch3d/transforms/rotation_conversions.py b/pytorch3d/transforms/rotation_conversions.py
index 1aec4fc6..19fb890d 100644
--- a/pytorch3d/transforms/rotation_conversions.py
+++ b/pytorch3d/transforms/rotation_conversions.py
@@ -95,7 +95,13 @@ def _sqrt_positive_part(x: torch.Tensor) -> torch.Tensor:
     Returns torch.sqrt(torch.max(0, x))
     but with a zero subgradient where x is 0.
     """
-    return torch.sqrt(F.relu(x))
+    ret = torch.zeros_like(x)
+    positive_mask = x > 0
+    if torch.is_grad_enabled():
+        ret[positive_mask] = torch.sqrt(x[positive_mask])
+    else:
+        ret = torch.where(positive_mask, torch.sqrt(x), ret)
+    return ret
 
 
 def matrix_to_quaternion(matrix: torch.Tensor) -> torch.Tensor: