diff --git a/lisp/gnus/mail-source.el b/lisp/gnus/mail-source.el
index ce1cb6c89c8..7da2a0a441d 100644
--- a/lisp/gnus/mail-source.el
+++ b/lisp/gnus/mail-source.el
@@ -810,8 +810,8 @@ Deleting old (> %s day(s)) incoming mail file `%s'." diff bfile)
     (let ((from (format "%s:%s:%s" server user port))
 	  (mail-source-string (format "pop:%s@%s" user server))
 	  (process-environment (if server
-				   (append (list (concat "MAILHOST=" server))
-					   process-environment)
+				   (cons (concat "MAILHOST=" server)
+					 process-environment)
 				 process-environment))
 	  result)
       (when (eq authentication 'password)
@@ -880,8 +880,8 @@ Deleting old (> %s day(s)) incoming mail file `%s'." diff bfile)
     (let ((from (format "%s:%s:%s" server user port))
 	  (mail-source-string (format "pop:%s@%s" user server))
 	  (process-environment (if server
-				   (append (list (concat "MAILHOST=" server))
-					   process-environment)
+				   (cons (concat "MAILHOST=" server)
+					 process-environment)
 				 process-environment))
 	  result)
       (when (eq authentication 'password)