diff --git a/scripts/maint/practracker/includes.py b/scripts/maint/practracker/includes.py
index e9b02c35b0..7af378d5c0 100755
--- a/scripts/maint/practracker/includes.py
+++ b/scripts/maint/practracker/includes.py
@@ -173,6 +173,27 @@ def remove_self_edges(graph):
     for k in list(graph):
         graph[k] = [ d for d in graph[k] if d != k ]
 
+def closure(graph):
+    """Takes a directed graph in as an adjacency mapping (a mapping from
+       node to a list of the nodes to which it connects), and completes
+       its closure.
+    """
+    graph = graph.copy()
+    changed = False
+    for k in graph.keys():
+        graph[k] = set(graph[k])
+    while True:
+        for k in graph.keys():
+            sz = len(graph[k])
+            for v in list(graph[k]):
+                graph[k].update(graph.get(v, []))
+            if sz != len(graph[k]):
+                changed = True
+
+        if not changed:
+            return graph
+        changed = False
+
 def toposort(graph, limit=100):
     """Takes a directed graph in as an adjacency mapping (a mapping from
        node to a list of the nodes to which it connects).  Tries to
@@ -233,8 +254,25 @@ def walk_c_files(topdir="src"):
                     for err in consider_include_rules(fullpath, f):
                         yield err
 
+def check_subsys_file(fname, uses_dirs):
+    uses_closure = closure(uses_dirs)
+    ok = True
+    previous_subsystems = []
+    with open(fname) as f:
+        for line in f:
+            _, name, fname = line.split()
+            fname = re.sub(r'^.*/src/', "", fname)
+            fname = re.sub(r'^src/', "", fname)
+            fname = re.sub(r'/[^/]*\.c', "", fname)
+            for prev in previous_subsystems:
+                if fname in uses_closure[prev]:
+                    print("INVERSION: {} uses {}".format(prev,fname))
+                    ok = False
+            previous_subsystems.append(fname)
+    return not ok
+
 def run_check_includes(topdir, list_unused=False, log_sorted_levels=False,
-                       list_advisories=False):
+                       list_advisories=False, check_subsystem_order=None):
     trouble = False
 
     for err in walk_c_files(topdir):
@@ -259,6 +297,11 @@ def run_check_includes(topdir, list_unused=False, log_sorted_levels=False,
         uses_dirs[rules.incpath] = rules.getAllowedDirectories()
 
     remove_self_edges(uses_dirs)
+
+    if check_subsystem_order:
+        if check_subsys_file(check_subsystem_order, uses_dirs):
+            sys.exit(1)
+
     all_levels = toposort(uses_dirs)
 
     if log_sorted_levels:
@@ -282,6 +325,8 @@ def main(argv):
                         help="List unused lines in .may_include files.")
     parser.add_argument("--list-advisories", action="store_true",
                         help="List advisories as well as forbidden includes")
+    parser.add_argument("--check-subsystem-order", action="store",
+                        help="Check a list of subsystems for ordering")
     parser.add_argument("topdir", default="src", nargs="?",
                         help="Top-level directory for the tor source")
     args = parser.parse_args(argv[1:])
@@ -289,7 +334,8 @@ def main(argv):
     run_check_includes(topdir=args.topdir,
                        log_sorted_levels=args.toposort,
                        list_unused=args.list_unused,
-                       list_advisories=args.list_advisories)
+                       list_advisories=args.list_advisories,
+                       check_subsystem_order=args.check_subsystem_order)
 
 if __name__ == '__main__':
     main(sys.argv)