diff --git a/ChangeLog b/ChangeLog
index 1403616e9a..5d8c035390 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-09-18  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Fix tzfile low-memory assertion failure
+	[BZ #21716]
+	* time/tzfile.c (__tzfile_read): Check for memory exhaustion
+	when registering time zone abbreviations.
+
 2018-09-18  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/unix/sysv/linux/bits/mman.h: New file.
diff --git a/time/tzfile.c b/time/tzfile.c
index 2a385b92bc..ea6e940303 100644
--- a/time/tzfile.c
+++ b/time/tzfile.c
@@ -410,7 +410,8 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
 
   /* First "register" all timezone names.  */
   for (i = 0; i < num_types; ++i)
-    (void) __tzstring (&zone_names[types[i].idx]);
+    if (__tzstring (&zone_names[types[i].idx]) == NULL)
+      goto ret_free_transitions;
 
   /* Find the standard and daylight time offsets used by the rule file.
      We choose the offsets in the types of each flavor that are