diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index d7ff432..1fdda95 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,12 @@
 Changelog
 =========
 
+Unreleased
+----------
+
+- Fix type hint for ``BasePurlType.allowed_qualifiers``
+  https://github.com/package-url/packageurl-python/pull/213
+
 0.17.6 (2025-11-24)
 -------------------
 
diff --git a/src/packageurl/validate.py b/src/packageurl/validate.py
index 45cf146..4ee81c3 100644
--- a/src/packageurl/validate.py
+++ b/src/packageurl/validate.py
@@ -26,6 +26,8 @@
 Validate each type according to the PURL spec type definitions
 """
 
+from typing import Set
+
 
 class BasePurlType:
     """
@@ -50,7 +52,7 @@ class BasePurlType:
     namespace_requirement: str
     """"States if this namespace is required, optional, or prohibited."""
 
-    allowed_qualifiers: dict = {"repository_url", "arch"}
+    allowed_qualifiers: Set[str] = {"repository_url", "arch"}
     """Set of allowed qualifier keys for this PURL type."""
 
     namespace_case_sensitive: bool = True