diff --git a/taskcluster/taskgraph/transforms/beetmover_repackage.py b/taskcluster/taskgraph/transforms/beetmover_repackage.py
index 4289aeb72f43..66d99df7575c 100644
--- a/taskcluster/taskgraph/transforms/beetmover_repackage.py
+++ b/taskcluster/taskgraph/transforms/beetmover_repackage.py
@@ -334,8 +334,8 @@ def generate_partials_upstream_artifacts(job, artifacts, platform, locale=None):
     upstream_artifacts = [{
         'taskId': {'task-reference': '<partials-signing>'},
         'taskType': 'signing',
-        'paths': ["{}/{}".format(artifact_prefix, p)
-                  for p in artifacts],
+        'paths': ["{}/{}".format(artifact_prefix, path)
+                  for path, _ in artifacts],
         'locale': locale or 'en-US',
     }]
 
diff --git a/taskcluster/taskgraph/transforms/partials_signing.py b/taskcluster/taskgraph/transforms/partials_signing.py
index 4198a0ad938a..098b188139b0 100644
--- a/taskcluster/taskgraph/transforms/partials_signing.py
+++ b/taskcluster/taskgraph/transforms/partials_signing.py
@@ -33,14 +33,36 @@ def generate_upstream_artifacts(job, release_history, platform, locale=None):
     upstream_artifacts = [{
         "taskId": {"task-reference": '<partials>'},
         "taskType": 'partials',
-        "paths": ["{}/{}".format(artifact_prefix, p)
-                  for p in artifacts],
+        "paths": [
+            "{}/{}".format(artifact_prefix, path)
+            for path, version in artifacts
+            # TODO Use mozilla-version to avoid comparing strings. Otherwise Firefox 100 will be
+            # considered smaller than Firefox 56
+            if version is None or version >= '56'
+        ],
         "formats": ["mar_sha384"],
     }]
 
+    old_mar_upstream_artifacts = {
+        "taskId": {"task-reference": '<partials>'},
+        "taskType": 'partials',
+        "paths": [
+            "{}/{}".format(artifact_prefix, path)
+            for path, version in artifacts
+            # TODO Use mozilla-version to avoid comparing strings. Otherwise Firefox 100 will be
+            # considered smaller than Firefox 56
+            if version is not None and version < '56'
+        ],
+        "formats": ["mar"],
+    }
+
+    if old_mar_upstream_artifacts["paths"]:
+        upstream_artifacts.append(old_mar_upstream_artifacts)
+
     return upstream_artifacts
 
 
+
 @transforms.add
 def make_task_description(config, jobs):
     for job in jobs:
@@ -81,7 +103,11 @@ def make_task_description(config, jobs):
         signing_cert_scope = get_signing_cert_scope_per_platform(
             build_platform, is_nightly, config
         )
+
         scopes = [signing_cert_scope, 'project:releng:signing:format:mar_sha384']
+        if any("mar" in upstream_details["formats"] for upstream_details in upstream_artifacts):
+            scopes.append('project:releng:signing:format:mar')
+
         task = {
             'label': label,
             'description': "{} Partials".format(
diff --git a/taskcluster/taskgraph/util/partials.py b/taskcluster/taskgraph/util/partials.py
index 2c92fa5f641e..80f6cea5028a 100644
--- a/taskcluster/taskgraph/util/partials.py
+++ b/taskcluster/taskgraph/util/partials.py
@@ -91,7 +91,10 @@ def get_builds(release_history, platform, locale):
 
 def get_partials_artifacts(release_history, platform, locale):
     platform = _sanitize_platform(platform)
-    return release_history.get(platform, {}).get(locale, {}).keys()
+    return [
+        (artifact, details.get('previousVersion', None))
+        for artifact, details in release_history.get(platform, {}).get(locale, {}).items()
+    ]
 
 
 def get_partials_artifact_map(release_history, platform, locale):