Backport fix from 51683.
diff --git a/Modules/_cursesmodule.c b/Modules/_cursesmodule.c
index 2921d53..aeb1ef5 100644
--- a/Modules/_cursesmodule.c
+++ b/Modules/_cursesmodule.c
@@ -2334,6 +2334,10 @@
 	}
 
 	result = tparm(fmt,i1,i2,i3,i4,i5,i6,i7,i8,i9);
+	if (!result) {
+		PyErr_SetString(PyCursesError, "tparm() returned NULL");
+  		return NULL;
+	}
 
 	return PyString_FromString(result);
 }