diff --git a/libc/include/sys/_errdefs.h b/libc/include/sys/_errdefs.h
index e27ab7a..51d921b 100644
--- a/libc/include/sys/_errdefs.h
+++ b/libc/include/sys/_errdefs.h
@@ -36,6 +36,7 @@
 #ifndef __BIONIC_ERRDEF
 #error "__BIONIC_ERRDEF must be defined before including this file"
 #endif
+__BIONIC_ERRDEF( 0              ,   0, "Success" )
 __BIONIC_ERRDEF( EPERM          ,   1, "Operation not permitted" )
 __BIONIC_ERRDEF( ENOENT         ,   2, "No such file or directory" )
 __BIONIC_ERRDEF( ESRCH          ,   3, "No such process" )
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)