diff --git a/asu/api.py b/asu/api.py
index 83e0f108..401e986c 100644
--- a/asu/api.py
+++ b/asu/api.py
@@ -109,7 +109,9 @@ def validate_request(req):
         )
 
     if req.get("packages_versions") and not req.get("packages"):
-        req["packages"] = req["packages_versions"].keys()
+        req["packages"] = set(req["packages_versions"].keys())
+    else:
+        req["packages"] = set(req.get("packages", []))
 
     r = get_redis()
 
diff --git a/asu/common.py b/asu/common.py
index b3cb4168..f929719f 100644
--- a/asu/common.py
+++ b/asu/common.py
@@ -197,7 +197,7 @@ def get_container_version_tag(version: str) -> str:
     return version
 
 
-def diff_packages(requested_packages: list, default_packages: set):
+def diff_packages(requested_packages: set, default_packages: set):
     """Return a list of packages to install and remove
 
     Args:
@@ -206,7 +206,6 @@ def diff_packages(requested_packages: list, default_packages: set):
 
     Returns:
         set: Set of packages to install and remove"""
-    requested_packages = set(requested_packages)
     remove_packages = default_packages - requested_packages
     return requested_packages | set(
         map(lambda p: f"-{p}".replace("--", "-"), remove_packages)