diff --git a/shared/nm-utils/nm-shared-utils.c b/shared/nm-utils/nm-shared-utils.c
index 13a1a35f6e..1554d4cd07 100644
--- a/shared/nm-utils/nm-shared-utils.c
+++ b/shared/nm-utils/nm-shared-utils.c
@@ -974,8 +974,7 @@ _char_lookup_table_init (guint8 lookup[static 256],
 /**
  * nm_utils_strsplit_set_full:
  * @str: the string to split.
- * @delimiters: the set of delimiters. If %NULL, defaults to " \t\n",
- *   like bash's $IFS.
+ * @delimiters: the set of delimiters.
  * @flags: additional flags for controlling the operation.
  *
  * This is a replacement for g_strsplit_set() which avoids copying
@@ -1017,8 +1016,10 @@ nm_utils_strsplit_set_full (const char *str,
 		return NULL;
 
 	/* initialize lookup table for delimiter */
-	if (!delimiters)
+	if (!delimiters) {
+		nm_assert_not_reached ();
 		delimiters = " \t\n";
+	}
 
 	_char_lookup_table_init (delimiters_table, delimiters);
 
diff --git a/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c b/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
index 8d39f827ca..93d48dfdd4 100644
--- a/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
+++ b/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
@@ -4147,7 +4147,7 @@ parse_ethtool_option (const char *value,
 	gs_free const char **words = NULL;
 	guint i;
 
-	words = nm_utils_strsplit_set (value, NULL);
+	words = nm_utils_strsplit_set (value, " \t\n");
 	if (!words)
 		return;