diff --git a/src/archive.lisp b/src/archive.lisp
index 7afd27c..6d35a58 100644
--- a/src/archive.lisp
+++ b/src/archive.lisp
@@ -4,13 +4,6 @@
 
 (in-package #:pgloader.archive)
 
-(defparameter *default-tmpdir*
-  (let* ((tmpdir (uiop:getenv "TMPDIR"))
-	 (tmpdir (or (and tmpdir (probe-file tmpdir)) "/tmp"))
-	 (tmpdir (fad:pathname-as-directory tmpdir)))
-    (fad:pathname-as-directory (merge-pathnames "pgloader" tmpdir)))
-  "Place where to fetch and expand archives on-disk.")
-
 (defun http-fetch-file (url &key (tmpdir *default-tmpdir*))
   "Download a file from URL into TMPDIR."
 
diff --git a/src/main.lisp b/src/main.lisp
index bc16639..cd67d14 100644
--- a/src/main.lisp
+++ b/src/main.lisp
@@ -86,10 +86,14 @@
 	(setf *root-dir* (fad:pathname-as-directory root-dir))
 	(mkdir-or-die *root-dir* debug)
 
+	;; Set parameters that come from the environement
+	(init-params-from-environment)
+
 	;; Then process options
 	(when debug
 	  (format t "sb-impl::*default-external-format* ~s~%"
-		  sb-impl::*default-external-format*))
+		  sb-impl::*default-external-format*)
+	  (format t "tmpdir: ~s~%" *default-tmpdir*))
 
 	(when version
 	  (format t "pgloader version ~s~%" *version-string*))
diff --git a/src/params.lisp b/src/params.lisp
index 041f684..b8aac0e 100644
--- a/src/params.lisp
+++ b/src/params.lisp
@@ -23,6 +23,8 @@
 	   #:*myconn-user*
 	   #:*myconn-pass*
 	   #:*state*
+	   #:*default-tmpdir*
+	   #:init-params-from-environment
 	   #:getenv-default))
 
 (in-package :pgloader.params)
@@ -83,3 +85,26 @@
 (defparameter *myconn-port* 3306)
 (defparameter *myconn-user* (uiop:getenv "USER"))
 (defparameter *myconn-pass* nil)
+
+;;;
+;;; Archive processing: downloads and unzip.
+;;;
+(defparameter *default-tmpdir*
+  (let* ((tmpdir (uiop:getenv "TMPDIR"))
+	 (tmpdir (or (and tmpdir (probe-file tmpdir)) "/tmp"))
+	 (tmpdir (fad:pathname-as-directory tmpdir)))
+    (fad:pathname-as-directory (merge-pathnames "pgloader" tmpdir)))
+  "Place where to fetch and expand archives on-disk.")
+
+;;;
+;;; Run time initialisation of ENV provided parameters
+;;;
+;;; The command parser dynamically inspect the environment when building the
+;;; connection parameters, so that we don't need to provision for those here.
+;;;
+(defun init-params-from-environment ()
+  "Some of our parameters get their default value from the env. Do that at
+   runtime when using a compiled binary."
+  (setf *default-tmpdir*
+	(fad:pathname-as-directory
+	 (getenv-default "TMPDIR" *default-tmpdir*))))