diff --git a/lib/log.js b/lib/log.js
index 4ddc505..3f50230 100644
--- a/lib/log.js
+++ b/lib/log.js
@@ -93,11 +93,11 @@ class Logger {
   }
 
   set level (level) {
-    this.#level = this.#levels.get(level)?.id || null
+    this.#level = (this.#levels.get(level) && this.#levels.get(level).id) || null
   }
 
   isVisible (level) {
-    return this.level?.index <= this.#levels.get(level)?.index || -1
+    return (this.level && this.level.index <= (this.#levels.get(level) && this.#levels.get(level).index)) || -1
   }
 
   #onLog (...args) {
@@ -124,7 +124,7 @@ class Logger {
   }
 
   #color (str, { fg, bg, inverse }) {
-    if (!this.#stream?.isTTY) {
+    if (!this.#stream || !this.#stream.isTTY) {
       return str
     }
 
@@ -136,7 +136,7 @@ class Logger {
   }
 
   #log (levelId, msgPrefix, ...args) {
-    if (!this.isVisible(levelId) || typeof this.#stream?.write !== 'function') {
+    if (!this.isVisible(levelId) || (this.#stream && typeof this.#stream.write !== 'function')) {
       return
     }