diff --git a/libprocessgroup/task_profiles.cpp b/libprocessgroup/task_profiles.cpp
index 7a04100ac..27060aed5 100644
--- a/libprocessgroup/task_profiles.cpp
+++ b/libprocessgroup/task_profiles.cpp
@@ -215,6 +215,9 @@ bool SetAttributeAction::ExecuteForTask(int tid) const {
                 return false;
             }
         }
+        // The PLOG() statement below uses the error code stored in `errno` by
+        // WriteStringToFile() because access() only overwrites `errno` if it fails
+        // and because this code is only reached if the access() function returns 0.
         PLOG(ERROR) << "Failed to write '" << value_ << "' to " << path;
         return false;
     }