diff --git a/libc/string/strerror_r.c b/libc/string/strerror_r.c
index f43d417..2f26f17 100644
--- a/libc/string/strerror_r.c
+++ b/libc/string/strerror_r.c
@@ -21,7 +21,7 @@
 
     for (;;)
     {
-        if (strings[nn].code == 0)
+        if (strings[nn].msg == NULL)
             break;
 
         if (strings[nn].code == code)