diff --git a/update_attempter.cc b/update_attempter.cc
index 05cfd49..6768529 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -193,7 +193,8 @@
     return;
 
   if (stat("/etc/lsb-release", &sb) != 0) {
-    PLOG(ERROR) << "Error getting file status for /etc/lsb-release";
+    PLOG(ERROR) << "Error getting file status for /etc/lsb-release "
+                << "(Note: this may happen in some unit tests)";
     return;
   }
 
@@ -202,7 +203,8 @@
   base::TimeDelta age = now - lsb_release_timestamp;
   if (age.InSeconds() < 0) {
     LOG(ERROR) << "The OS age (" << utils::FormatTimeDelta(age)
-               << ") is negative. Maybe the clock is wrong?";
+               << ") is negative. Maybe the clock is wrong? "
+               << "(Note: this may happen in some unit tests.)";
     return;
   }