diff --git a/libc/system_properties/contexts_serialized.cpp b/libc/system_properties/contexts_serialized.cpp
index 6ccd46c..f05aaa0 100644
--- a/libc/system_properties/contexts_serialized.cpp
+++ b/libc/system_properties/contexts_serialized.cpp
@@ -66,18 +66,12 @@
 }
 
 bool ContextsSerialized::MapSerialPropertyArea(bool access_rw, bool* fsetxattr_failed) {
-  char filename[PROP_FILENAME_MAX];
-  int len = async_safe_format_buffer(filename, sizeof(filename), "%s/properties_serial", filename_);
-  if (len < 0 || len >= PROP_FILENAME_MAX) {
-    serial_prop_area_ = nullptr;
-    return false;
-  }
-
+  PropertiesFilename filename(filename_, "properties_serial");
   if (access_rw) {
-    serial_prop_area_ =
-        prop_area::map_prop_area_rw(filename, "u:object_r:properties_serial:s0", fsetxattr_failed);
+    serial_prop_area_ = prop_area::map_prop_area_rw(
+        filename.c_str(), "u:object_r:properties_serial:s0", fsetxattr_failed);
   } else {
-    serial_prop_area_ = prop_area::map_prop_area(filename);
+    serial_prop_area_ = prop_area::map_prop_area(filename.c_str());
   }
   return serial_prop_area_;
 }