diff --git a/guix/bzr-download.scm b/guix/bzr-download.scm
index d30833c5d7..010e0decff 100644
--- a/guix/bzr-download.scm
+++ b/guix/bzr-download.scm
@@ -75,6 +75,9 @@ HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
                       #:env-vars
                       `(("bzr url" . ,(bzr-reference-url ref))
                         ("bzr reference" . ,(bzr-reference-revision ref)))
+                      #:leaked-env-vars '("http_proxy" "https_proxy"
+                                          "LC_ALL" "LC_MESSAGES" "LANG"
+                                          "COLUMNS")
                       #:system system
                       #:local-build? #t  ;don't offload repo branching
                       #:hash-algo hash-algo
diff --git a/guix/cvs-download.scm b/guix/cvs-download.scm
index 8b46f8ef8c..cb42103aae 100644
--- a/guix/cvs-download.scm
+++ b/guix/cvs-download.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2015, 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2014 Sree Harsha Totakura <sreeharsha@totakura.in>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
 ;;;
@@ -92,6 +92,9 @@ HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
 
   (mlet %store-monad ((guile (package->derivation guile system)))
     (gexp->derivation (or name "cvs-checkout") build
+                      #:leaked-env-vars '("http_proxy" "https_proxy"
+                                          "LC_ALL" "LC_MESSAGES" "LANG"
+                                          "COLUMNS")
                       #:system system
                       #:hash-algo hash-algo
                       #:hash hash
diff --git a/guix/git-download.scm b/guix/git-download.scm
index c62bb8ad0f..1eae035fc4 100644
--- a/guix/git-download.scm
+++ b/guix/git-download.scm
@@ -157,6 +157,9 @@ HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
                         ("git commit" . ,(git-reference-commit ref))
                         ("git recursive?" . ,(object->string
                                               (git-reference-recursive? ref))))
+                      #:leaked-env-vars '("http_proxy" "https_proxy"
+                                          "LC_ALL" "LC_MESSAGES" "LANG"
+                                          "COLUMNS")
 
                       #:system system
                       #:local-build? #t           ;don't offload repo cloning
diff --git a/guix/hg-download.scm b/guix/hg-download.scm
index 6b25b87b6b..4cdc1a780a 100644
--- a/guix/hg-download.scm
+++ b/guix/hg-download.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2015, 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2016 Ricardo Wurmus <rekado@elephly.net>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -92,6 +92,9 @@ HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
 
   (mlet %store-monad ((guile (package->derivation guile system)))
     (gexp->derivation (or name "hg-checkout") build
+                      #:leaked-env-vars '("http_proxy" "https_proxy"
+                                          "LC_ALL" "LC_MESSAGES" "LANG"
+                                          "COLUMNS")
                       #:system system
                       #:local-build? #t           ;don't offload repo cloning
                       #:hash-algo hash-algo
diff --git a/guix/svn-download.scm b/guix/svn-download.scm
index 5c25437059..4139cbc2e2 100644
--- a/guix/svn-download.scm
+++ b/guix/svn-download.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014, 2015, 2016, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2014 Sree Harsha Totakura <sreeharsha@totakura.in>
 ;;; Copyright © 2017, 2019 Ricardo Wurmus <rekado@elephly.net>
 ;;;
@@ -131,6 +131,9 @@ HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
 
   (mlet %store-monad ((guile (package->derivation guile system)))
     (gexp->derivation (or name "svn-checkout") build
+                      #:leaked-env-vars '("http_proxy" "https_proxy"
+                                          "LC_ALL" "LC_MESSAGES" "LANG"
+                                          "COLUMNS")
                       #:system system
                       #:hash-algo hash-algo
                       #:hash hash