diff --git a/src/vim9execute.c b/src/vim9execute.c
index c7f0e67..5022000 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -2461,8 +2461,14 @@
 		otv = class->class_members_tv;
 	    }
 
-	    clear_tv(&otv[lidx]);
-	    otv[lidx] = *tv;
+	    if (otv != NULL)
+	    {
+		clear_tv(&otv[lidx]);
+		otv[lidx] = *tv;
+	    }
+	    else
+		status = FAIL;
+
 	}
 	else
 	{