diff --git a/Misc/NEWS b/Misc/NEWS
index e8b68e0..29bc276 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
 Core and Builtins
 -----------------
 
+- Restore GIL in nis_cat in case of error.
+
 - Issue #8530: Prevent stringlib fastsearch from reading beyond the front
   of an array.
 
diff --git a/Modules/nismodule.c b/Modules/nismodule.c
index 04d8570..6acab63 100644
--- a/Modules/nismodule.c
+++ b/Modules/nismodule.c
@@ -124,6 +124,7 @@
             PyErr_Clear();
             Py_XDECREF(key);
             Py_XDECREF(val);
+            indata->state = PyEval_SaveThread();
             return 1;
         }
         err = PyDict_SetItem(indata->dict, key, val);