diff --git a/tools/mlock_report.py b/tools/mlock_report.py
index 1b081bbe6f..8cbda15895 100644
--- a/tools/mlock_report.py
+++ b/tools/mlock_report.py
@@ -6,7 +6,7 @@ import psutil
 
 
 LCK_SUMMARY_REGEX = re.compile(
-    "^VmLck:\s+(?P<locked>[\d]+)\s+kB", re.MULTILINE)
+    r"^VmLck:\s+(?P<locked>[\d]+)\s+kB", re.MULTILINE)
 
 
 def main():