diff --git a/src/libnm-glib-aux/nm-str-buf.h b/src/libnm-glib-aux/nm-str-buf.h
index b43b206f83..7a7f580ccb 100644
--- a/src/libnm-glib-aux/nm-str-buf.h
+++ b/src/libnm-glib-aux/nm-str-buf.h
@@ -504,4 +504,11 @@ nm_str_buf_destroy(NMStrBuf *strbuf)
 
 #define nm_auto_str_buf nm_auto(nm_str_buf_destroy)
 
+static inline gboolean
+nm_str_buf_utf8_validate(NMStrBuf *strbuf)
+{
+    _nm_str_buf_assert(strbuf);
+    return strbuf->_priv_len == 0 || g_utf8_validate(strbuf->_priv_str, strbuf->_priv_len, NULL);
+}
+
 #endif /* __NM_STR_BUF_H__ */