diff --git a/pavement.py b/pavement.py
index 0364f48..b84b011 100644
--- a/pavement.py
+++ b/pavement.py
@@ -119,8 +119,8 @@ def compile_file(fullname, ddir=None, force=0, rx=None, quiet=0):
             if not force:
                 try:
                     mtime = int(os.stat(fullname).st_mtime)
-                    expect = struct.pack('<4sl', imp.get_magic(), mtime)
-                    cfile = fullname + (__debug__ and 'c' or 'o')
+                    expect = struct.pack('<4sl', importlib.util.MAGIC_NUMBER, mtime)
+                    cfile = fullname + ('c' if __debug__ else 'o')
                     with open(cfile, 'rb') as chandle:
                         actual = chandle.read(8)
                     if expect == actual: