diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index 6d5d745bc8..729850839b 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -1,6 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2015, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2017 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2017, 2018 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2018 Konrad Hinsen <konrad.hinsen@fastmail.net>
 ;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
@@ -69,7 +68,7 @@
         (compressor "lzip"  ".lz"
                     #~(#+(file-append lzip "/bin/lzip") "-9"))
         (compressor "xz"    ".xz"
-                    #~(#+(file-append xz "/bin/xz") "-e -T0"))
+                    #~(#+(file-append xz "/bin/xz") "-e"))
         (compressor "bzip2" ".bz2"
                     #~(#+(file-append bzip2 "/bin/bzip2") "-9"))
         (compressor "none" "" #f)))
@@ -77,7 +76,7 @@
 ;; This one is only for use in this module, so don't put it in %compressors.
 (define bootstrap-xz
   (compressor "bootstrap-xz" ".xz"
-              #~(#+(file-append %bootstrap-coreutils&co "/bin/xz") "-e -T0")))
+              #~(#+(file-append %bootstrap-coreutils&co "/bin/xz") "-e")))
 
 (define (lookup-compressor name)
   "Return the compressor object called NAME.  Error out if it could not be
diff --git a/guix/utils.scm b/guix/utils.scm
index 200bb69e03..9bad06d52f 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -5,7 +5,6 @@
 ;;; Copyright © 2014 Ian Denhardt <ian@zenhack.net>
 ;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
 ;;; Copyright © 2015 David Thompson <davet@gnu.org>
-;;; Copyright © 2017 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2018 Marius Bakke <mbakke@fastmail.com>
 ;;;
@@ -176,7 +175,7 @@ a symbol such as 'xz."
   (match compression
     ((or #f 'none) (values input '()))
     ('bzip2        (filtered-port `(,%bzip2 "-dc") input))
-    ('xz           (filtered-port `(,%xz "-dc" "-T0") input))
+    ('xz           (filtered-port `(,%xz "-dc") input))
     ('gzip         (filtered-port `(,%gzip "-dc") input))
     (else          (error "unsupported compression scheme" compression))))
 
@@ -186,7 +185,7 @@ a symbol such as 'xz."
   (match compression
     ((or #f 'none) (values input '()))
     ('bzip2        (filtered-port `(,%bzip2 "-c") input))
-    ('xz           (filtered-port `(,%xz "-c" "-T0") input))
+    ('xz           (filtered-port `(,%xz "-c") input))
     ('gzip         (filtered-port `(,%gzip "-c") input))
     (else          (error "unsupported compression scheme" compression))))
 
@@ -243,7 +242,7 @@ program--e.g., '(\"--fast\")."
   (match compression
     ((or #f 'none) (values output '()))
     ('bzip2        (filtered-output-port `(,%bzip2 "-c" ,@options) output))
-    ('xz           (filtered-output-port `(,%xz "-c" "-T0" ,@options) output))
+    ('xz           (filtered-output-port `(,%xz "-c" ,@options) output))
     ('gzip         (filtered-output-port `(,%gzip "-c" ,@options) output))
     (else          (error "unsupported compression scheme" compression))))