diff --git a/scripts/wk/hw/obj.py b/scripts/wk/hw/obj.py
index bf6eef37..2a978be7 100644
--- a/scripts/wk/hw/obj.py
+++ b/scripts/wk/hw/obj.py
@@ -155,7 +155,7 @@ class CpuRam(BaseObj):
       cmd = (
         'ioreg -c IOPlatformExpertDevice -d 2'
         "| awk '/IOPlatformSerialNumber/ {print $3}'"
-        '| sed s/"//g'
+        "| sed 's/\"//g'"
         )
       proc = run_program(cmd, check=False, shell=True)
       self.serial = proc.stdout.strip()