diff --git a/scripts/maint/practracker/util.py b/scripts/maint/practracker/util.py
index b0ca73b997..5a8876a0f6 100644
--- a/scripts/maint/practracker/util.py
+++ b/scripts/maint/practracker/util.py
@@ -2,15 +2,24 @@ import os
 
 # We don't want to run metrics for unittests, automatically-generated C files,
 # external libraries or git leftovers.
-EXCLUDE_SOURCE_DIRS = {"/src/test/", "/src/trunnel/", "/src/ext/", "/.git/"}
+EXCLUDE_SOURCE_DIRS = {"src/test/", "src/trunnel/", "src/rust/",
+                       "src/ext/", ".git/"}
+
+def _norm(p):
+    return os.path.normcase(os.path.normpath(p))
 
 def get_tor_c_files(tor_topdir):
     """
     Return a list with the .c filenames we want to get metrics of.
     """
     files_list = []
+    exclude_dirs = { _norm(os.path.join(tor_topdir, p)) for p in EXCLUDE_SOURCE_DIRS }
+
 
     for root, directories, filenames in os.walk(tor_topdir):
+        # Remove all the directories that are excluded.
+        directories[:] = [ d for d in directories
+                           if _norm(os.path.join(root,d)) not in exclude_dirs ]
         directories.sort()
         filenames.sort()
         for filename in filenames:
@@ -18,10 +27,7 @@ def get_tor_c_files(tor_topdir):
             if not filename.endswith(".c"):
                 continue
 
-            # Exclude the excluded paths
             full_path = os.path.join(root,filename)
-            if any(os.path.normcase(exclude_dir) in full_path for exclude_dir in EXCLUDE_SOURCE_DIRS):
-                continue
 
             files_list.append(full_path)