diff --git a/src/ex_getln.c b/src/ex_getln.c
index dc933d7..36d148e 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -4294,7 +4294,8 @@
 	}
     }
 
-    rettv->vval.v_number = set_cmdline_str(argvars[0].vval.v_string, pos);
+    // Use tv_get_string() to handle a NULL string like an empty string.
+    rettv->vval.v_number = set_cmdline_str(tv_get_string(&argvars[0]), pos);
 }
 
 /*