diff --git a/src/scripts/classes/mapping/post.ts b/src/scripts/classes/mapping/post.ts
index f9dfaaf..c8f9da5 100644
--- a/src/scripts/classes/mapping/post.ts
+++ b/src/scripts/classes/mapping/post.ts
@@ -101,6 +101,9 @@ export default class Post implements ILazy {
     // Check login
     if (!shared.isLogged) throw new UserNotLogged(USER_NOT_LOGGED);
 
+    // Check ID
+    if (!this.id && this.id < 1) throw new Error("Invalid post ID");
+
     // Fetch HTML page containing the post
     const url = new URL(this.id.toString(), urls.POSTS).toString();
     const response = await fetchHTML(url);
diff --git a/src/scripts/classes/mapping/thread.ts b/src/scripts/classes/mapping/thread.ts
index 40d9a87..e061a1f 100644
--- a/src/scripts/classes/mapping/thread.ts
+++ b/src/scripts/classes/mapping/thread.ts
@@ -230,6 +230,9 @@ export default class Thread implements ILazy {
     // Check login
     if (!shared.isLogged) throw new UserNotLogged(USER_NOT_LOGGED);
 
+    // Check ID
+    if (!this.id && this.id < 1) throw new Error("Invalid thread ID");
+
     // Prepare the url
     this._url = new URL(this.id.toString(), urls.THREADS).toString();