diff --git a/libiberty/ChangeLog b/libiberty/ChangeLog
index dc5d9971f68..8293fa9ac56 100644
--- a/libiberty/ChangeLog
+++ b/libiberty/ChangeLog
@@ -1,3 +1,7 @@
+2018-07-30  Tom Tromey  <tom@tromey.com>
+
+	* cplus-dem.c (remember_Btype): Don't call memcpy with LEN==0.
+
 2018-07-26  Martin Liska  <mliska@suse.cz>
 
         PR lto/86548
diff --git a/libiberty/cplus-dem.c b/libiberty/cplus-dem.c
index 6d58bd899bf..4f29d54d089 100644
--- a/libiberty/cplus-dem.c
+++ b/libiberty/cplus-dem.c
@@ -4471,7 +4471,8 @@ remember_Btype (struct work_stuff *work, const char *start,
   char *tem;
 
   tem = XNEWVEC (char, len + 1);
-  memcpy (tem, start, len);
+  if (len > 0)
+    memcpy (tem, start, len);
   tem[len] = '\0';
   work -> btypevec[index] = tem;
 }