diff --git a/CHANGES/903.bugfix b/CHANGES/903.bugfix
new file mode 100644
index 000000000..5bb14b477
--- /dev/null
+++ b/CHANGES/903.bugfix
@@ -0,0 +1 @@
+Optimize mode can now take effect, when switching from mirrored to not mirrored mode between syncs.
diff --git a/pulp_deb/app/tasks/synchronizing.py b/pulp_deb/app/tasks/synchronizing.py
index e5ccac9a9..87e8cace0 100644
--- a/pulp_deb/app/tasks/synchronizing.py
+++ b/pulp_deb/app/tasks/synchronizing.py
@@ -546,7 +546,6 @@ def __init__(self, remote, optimize, mirror, previous_repo_version, *args, **kwa
         self.remote = remote
         self.optimize = optimize
         self.previous_repo_version = previous_repo_version
-        self.previous_sync_info = defaultdict(dict, previous_repo_version.info)
         self.sync_info = defaultdict()
         self.sync_info["remote_options"] = self._gen_remote_options()
         self.sync_info["sync_options"] = {
@@ -554,11 +553,14 @@ def __init__(self, remote, optimize, mirror, previous_repo_version, *args, **kwa
             "mirror": mirror,
         }
         self.parsed_url = urlparse(remote.url)
-        self.sync_options_unchanged = (
-            self.previous_sync_info["remote_options"] == self.sync_info["remote_options"]
-            and self.previous_sync_info["sync_options"]["mirror"]
-            == self.sync_info["sync_options"]["mirror"]
-        )
+        if self.optimize:
+            previous_sync_info = defaultdict(dict, self.previous_repo_version.info)
+            if not previous_sync_info["remote_options"] == self.sync_info["remote_options"]:
+                log.info(_("Setting optimize=False since the remote options have changed."))
+                self.optimize = False
+            if mirror and not previous_sync_info["sync_options"]["mirror"]:
+                log.info(_("Setting optimize=False since this sync switches to mirror=True."))
+                self.optimize = False
 
     async def run(self):
         """
@@ -618,7 +620,7 @@ async def _handle_distribution(self, distribution):
         release_file = await self._create_unit(release_file_dc)
         if release_file is None:
             return
-        if self.optimize and self.sync_options_unchanged:
+        if self.optimize:
             previous_release_file = await _get_previous_release_file(
                 self.previous_repo_version, distribution
             )
@@ -899,7 +901,7 @@ async def _handle_package_index(
             else:
                 raise NoPackageIndexFile(relative_dir=package_index_dir)
 
-        if self.optimize and self.sync_options_unchanged:
+        if self.optimize:
             previous_package_index = await _get_previous_package_index(
                 self.previous_repo_version, relative_path
             )