diff --git a/core/dbt/events/types.py b/core/dbt/events/types.py
index c50aba9085d..04f7ddd961e 100644
--- a/core/dbt/events/types.py
+++ b/core/dbt/events/types.py
@@ -1517,6 +1517,14 @@ def message(self) -> str:
         return f"Found duplicate package in packages.yml, removing: {self.removed_package}"
 
 
+class DepsLockfileRegenerating(WarnLevel):
+    def code(self):
+        return "M034"
+
+    def message(self) -> str:
+        return f"Package lockfile is out of sync with packages.yml. Regenerating lockfile at: {self.lock_filepath}"
+
+
 class DepsScrubbedPackageName(WarnLevel):
     def code(self):
         return "M035"
diff --git a/core/dbt/task/deps.py b/core/dbt/task/deps.py
index cd5624a9c71..424739c9e9e 100644
--- a/core/dbt/task/deps.py
+++ b/core/dbt/task/deps.py
@@ -21,6 +21,7 @@
     DepsFoundDuplicatePackage,
     DepsInstallInfo,
     DepsListSubdirectory,
+    DepsLockfileRegenerating,
     DepsLockUpdating,
     DepsNoPackagesFound,
     DepsNotifyUpdatesAvailable,
@@ -220,6 +221,7 @@ def run(self) -> None:
             current_hash = _create_sha1_hash(self.project.packages.packages)
             previous_hash = load_yml_dict(lock_file_path).get(PACKAGE_LOCK_HASH_KEY, None)
             if previous_hash != current_hash:
+                fire_event(DepsLockfileRegenerating(lock_filepath=lock_file_path))
                 self.lock()
 
         # Early return when 'dbt deps --lock'