diff --git a/mozilla/nsprpub/pr/src/md/unix/unix_errors.c b/mozilla/nsprpub/pr/src/md/unix/unix_errors.c
index 7164675b06f..1ce52e686c4 100644
--- a/mozilla/nsprpub/pr/src/md/unix/unix_errors.c
+++ b/mozilla/nsprpub/pr/src/md/unix/unix_errors.c
@@ -383,9 +383,14 @@ void _MD_unix_map_rmdir_error(int err)
     PRErrorCode prError;
 
     switch (err) {
+        /*
+         * On AIX 4.3, ENOTEMPTY is defined as EEXIST.
+         */
+#if ENOTEMPTY != EEXIST
         case ENOTEMPTY:
             prError = PR_DIRECTORY_NOT_EMPTY_ERROR;
             break;
+#endif
         case EEXIST:
             prError = PR_DIRECTORY_NOT_EMPTY_ERROR;
             break;