diff --git a/ObsoleteFiles.inc b/ObsoleteFiles.inc
index 638b27b530f0..eb5a7785b69e 100644
--- a/ObsoleteFiles.inc
+++ b/ObsoleteFiles.inc
@@ -36,6 +36,10 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20210107: retire a.out support
+OLD_DIRS+=usr/lib/aout
+OLD_DIRS+=usr/lib/compat/aout
+
 # 20210105: remove non widechar version of clang
 OLD_LIBS+=lib/libncurses.so.9
 # 20210103: new clang import which bumps version from 11.0.0 to 11.0.1.
diff --git a/etc/mtree/BSD.usr.dist b/etc/mtree/BSD.usr.dist
index f643d5ad269f..375cf3a96447 100644
--- a/etc/mtree/BSD.usr.dist
+++ b/etc/mtree/BSD.usr.dist
@@ -34,8 +34,6 @@
         ..
     ..
     lib
-        aout
-        ..
         clang
             11.0.1
                 include
@@ -61,8 +59,6 @@
             ..
         ..
         compat
-            aout
-            ..
         ..
         dtrace
         ..