diff --git a/pixi.lock b/pixi.lock
index 0f3d998..10ff3c6 100644
--- a/pixi.lock
+++ b/pixi.lock
@@ -582,8 +582,8 @@ packages:
   timestamp: 1759948672799
 - pypi: ./
   name: autoio
-  version: 2025.10.2
-  sha256: 3f634db95d830ccba4294985049f1b752e7f7cfe50f8cd8b43ee0359a98be061
+  version: 2025.11.0
+  sha256: ff80070e26545c913d5bc7e0431f6a4cb195414a0ffd049725ac32ca97063e43
   requires_python: '>=3.11'
   editable: true
 - conda: https://conda.anaconda.org/conda-forge/linux-64/brotli-1.1.0-hb03c661_4.conda
diff --git a/pyproject.toml b/pyproject.toml
index 4fe73b7..428856c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "autoio"
-version = "2025.10.2"
+version = "2025.11.0"
 description = "I/O interfaces for external codes used by AutoMech"
 readme = "README.md"
 dependencies = []
diff --git a/src/projrot_io/util.py b/src/projrot_io/util.py
index 97e2853..43bb5c2 100644
--- a/src/projrot_io/util.py
+++ b/src/projrot_io/util.py
@@ -66,16 +66,16 @@ def _format_grad_str(geo, grad):
         :type grads: list
         :rtype: str
     """
-
     atom_list = []
     for i, (sym, _) in enumerate(geo):
         atom_list.append(int(ptab.to_number(sym)))
 
     # Format the strings for the xyz gradients
     full_grads_str = ''
-    for i, grads in enumerate(grad):
-        grads_str = f'{grads[0]:>14.8f}{grads[1]:>14.8f}{grads[2]:>14.8f}'
-        full_grads_str += f'{i+1:2d}{atom_list[i]:4d}{grads_str}\n'
+    if grad:
+        for i, grads in enumerate(grad):
+            grads_str = f'{grads[0]:>14.8f}{grads[1]:>14.8f}{grads[2]:>14.8f}'
+            full_grads_str += f'{i+1:2d}{atom_list[i]:4d}{grads_str}\n'
 
     return remove_trail_whitespace(full_grads_str)