diff --git a/scripts/pretty_print_stacks.py b/scripts/pretty_print_stacks.py
index d990d30..a1526d5 100755
--- a/scripts/pretty_print_stacks.py
+++ b/scripts/pretty_print_stacks.py
@@ -38,7 +38,7 @@
         return
 
     for line in out.splitlines():
-        m = re.match(b'(.*) at (.*):(([0-9]+)|\?)([^:]*)', line)
+        m = re.match(rb'(.*) at (.*):(([0-9]+)|\?)([^:]*)', line)
         if m is None:
             puts('%s\n' % line)
             return