diff --git a/src/middleware/accesslog.lisp b/src/middleware/accesslog.lisp
index 3524308..881be5e 100644
--- a/src/middleware/accesslog.lisp
+++ b/src/middleware/accesslog.lisp
@@ -12,7 +12,7 @@
            :default-formatter))
 (in-package :lack.middleware.accesslog)
 
-(defvar *lack-middleware-accesslog*
+(defparameter *lack-middleware-accesslog*
   (let ((no-body '#:no-body))
     (lambda (app &key
               (logger
diff --git a/src/middleware/auth/basic.lisp b/src/middleware/auth/basic.lisp
index 15ab7a7..c86acbf 100644
--- a/src/middleware/auth/basic.lisp
+++ b/src/middleware/auth/basic.lisp
@@ -7,7 +7,7 @@
                 :split-sequence))
 (in-package :lack.middleware.auth.basic)
 
-(defvar *lack-middleware-auth-basic*
+(defparameter *lack-middleware-auth-basic*
   (lambda (app &key authenticator (realm "restricted area"))
     (unless authenticator
       (error ":authenticator is required in lack-middleware-auth-basic"))
diff --git a/src/middleware/backtrace.lisp b/src/middleware/backtrace.lisp
index a5e7c97..7c14c82 100644
--- a/src/middleware/backtrace.lisp
+++ b/src/middleware/backtrace.lisp
@@ -6,7 +6,7 @@
   (:export :*lack-middleware-backtrace*))
 (in-package :lack.middleware.backtrace)
 
-(defvar *lack-middleware-backtrace*
+(defparameter *lack-middleware-backtrace*
   (lambda (app &key
             (output '*error-output*)
             result-on-error)
diff --git a/src/middleware/csrf.lisp b/src/middleware/csrf.lisp
index 1c28c80..1f6b6f9 100644
--- a/src/middleware/csrf.lisp
+++ b/src/middleware/csrf.lisp
@@ -11,7 +11,7 @@
            :csrf-html-tag))
 (in-package :lack.middleware.csrf)
 
-(defvar *lack-middleware-csrf*
+(defparameter *lack-middleware-csrf*
   (lambda (app &key (block-app #'return-400) one-time)
     (lambda (env)
       (block nil
diff --git a/src/middleware/mount.lisp b/src/middleware/mount.lisp
index 1298637..f98457c 100644
--- a/src/middleware/mount.lisp
+++ b/src/middleware/mount.lisp
@@ -4,7 +4,7 @@
   (:export :*lack-middleware-mount*))
 (in-package :lack.middleware.mount)
 
-(defvar *lack-middleware-mount*
+(defparameter *lack-middleware-mount*
   (lambda (app path mount-app)
     (let ((len (length path)))
       (lambda (env)
diff --git a/src/middleware/session.lisp b/src/middleware/session.lisp
index 820cb36..1d9f046 100644
--- a/src/middleware/session.lisp
+++ b/src/middleware/session.lisp
@@ -17,7 +17,7 @@
   (:export :*lack-middleware-session*))
 (in-package :lack.middleware.session)
 
-(defvar *lack-middleware-session*
+(defparameter *lack-middleware-session*
   (lambda (app &key
             (store (make-memory-store))
             (state (make-cookie-state)))
diff --git a/src/middleware/static.lisp b/src/middleware/static.lisp
index 7923f5b..b1be991 100644
--- a/src/middleware/static.lisp
+++ b/src/middleware/static.lisp
@@ -9,7 +9,7 @@
   (:export :*lack-middleware-static*))
 (in-package :lack.middleware.static)
 
-(defvar *lack-middleware-static*
+(defparameter *lack-middleware-static*
   (lambda (app &key path (root #P"./"))
     (etypecase path
       (null app)