diff --git a/tools/gen-postmortem-metadata.py b/tools/gen-postmortem-metadata.py
index f47b9c91d5..390753f09c 100644
--- a/tools/gen-postmortem-metadata.py
+++ b/tools/gen-postmortem-metadata.py
@@ -317,7 +317,8 @@ header = '''
 #include "src/objects/js-promise.h"
 #include "src/objects/js-regexp-string-iterator.h"
 
-using namespace v8::internal;
+namespace v8 {
+namespace internal {
 
 extern "C" {
 
@@ -333,6 +334,9 @@ STACK_FRAME_TYPE_LIST(FRAME_CONST)
 
 footer = '''
 }
+
+}
+}
 '''
 
 #