diff --git a/src/metatrain/experimental/soap_bpnn/spherical.py b/src/metatrain/experimental/soap_bpnn/spherical.py
index 9c72c179..d4e29178 100644
--- a/src/metatrain/experimental/soap_bpnn/spherical.py
+++ b/src/metatrain/experimental/soap_bpnn/spherical.py
@@ -156,6 +156,9 @@ def forward(
             )
         elif self.o3_lambda == 1:
             basis = self.vector_basis(systems, selected_atoms)
+            basis = basis / torch.sqrt(
+                torch.sum(torch.square(basis), dim=-1, keepdim=True)
+            )
         elif self.o3_lambda == 2:
             basis = torch.empty(
                 (num_atoms, 5, 5),