diff --git a/basis/environment/environment-docs.factor b/basis/environment/environment-docs.factor
index 0bf7f2a11f..fee30fa8a6 100644
--- a/basis/environment/environment-docs.factor
+++ b/basis/environment/environment-docs.factor
@@ -54,10 +54,18 @@ HELP: os-envs
 HELP: set-os-envs
 { $values { "assoc" "an association mapping strings to strings" } }
 { $description "Replaces the current set of environment variables." }
+{ $warning "Leaks memory on Unix. If your program calls this function repeatedly, call " { $link set-os-envs-pointer } " with a malloced pointer and manage your memory instead." }
 { $notes
     "Names and values of environment variables are operating system-specific. Windows NT allows values up to 32766 characters in length."
 } ;
 
+HELP: set-os-envs-pointer
+{ $values { "malloc" "a pointer to memory from the heap obtained through " { $link malloc } " or similar" } }
+{ $description "Set then " { $link environ } " pointer. Factor must retain a pointer to this memory until exiting the program." }
+{ $notes
+    "Names and values of environment variables are operating system-specific."
+} ;
+
 HELP: set-os-env
 { $values { "value" string } { "key" string } }
 { $description "Set an environment variable." }
@@ -72,7 +80,7 @@ HELP: unset-os-env
     "Names and values of environment variables are operating system-specific."
 } ;
 
-{ os-env os-envs set-os-env unset-os-env set-os-envs change-os-env } related-words
+{ os-env os-envs set-os-env unset-os-env set-os-envs set-os-envs-pointer change-os-env } related-words
 
 
 ARTICLE: "environment" "Environment variables"
@@ -88,6 +96,10 @@ ARTICLE: "environment" "Environment variables"
     unset-os-env
     set-os-envs
     change-os-env
+}
+"Leak-free setting of all environment variables on Unix:"
+{ $subsections
+    set-os-envs-pointer
 } ;
 
 ABOUT: "environment"
diff --git a/basis/environment/environment.factor b/basis/environment/environment.factor
index ef94a32f90..92859349b7 100644
--- a/basis/environment/environment.factor
+++ b/basis/environment/environment.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2008 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: assocs combinators kernel sequences splitting system
-vocabs init vocabs.loader ;
+USING: assocs combinators init kernel sequences splitting
+system vocabs vocabs.loader ;
 IN: environment
 
 HOOK: os-env os ( key -- value )
@@ -14,6 +14,8 @@ HOOK: (os-envs) os ( -- seq )
 
 HOOK: (set-os-envs) os ( seq -- )
 
+HOOK: set-os-envs-pointer os ( malloc -- )
+
 : change-os-env ( key quot -- )
     [ [ os-env ] keep ] dip dip set-os-env ; inline
 
diff --git a/basis/environment/unix/unix.factor b/basis/environment/unix/unix.factor
index ba9d54a42d..94177913c1 100644
--- a/basis/environment/unix/unix.factor
+++ b/basis/environment/unix/unix.factor
@@ -21,8 +21,10 @@ M: unix (os-envs) ( -- seq )
 
 : set-void* ( value alien -- ) 0 set-alien-cell ;
 
+M: unix set-os-envs-pointer ( malloc -- ) environ set-void* ;
+
 M: unix (set-os-envs) ( seq -- )
-    utf8 strings>alien malloc-byte-array environ set-void* ;
+    utf8 strings>alien malloc-byte-array set-os-envs-pointer ;
 
 os {
     { macosx [ "environment.unix.macosx" require ] }