diff --git a/src/core/wee-completion.c b/src/core/wee-completion.c
index 96034f8d5..9eb0e1a45 100644
--- a/src/core/wee-completion.c
+++ b/src/core/wee-completion.c
@@ -885,7 +885,7 @@ completion_list_add_plugins_installed_cb (const void *pointer, void *data,
     (void) buffer;
 
     /* plugins in WeeChat extra lib dir */
-    extra_libdir = getenv ("WEECHAT_EXTRA_LIBDIR");
+    extra_libdir = getenv (WEECHAT_EXTRA_LIBDIR);
     if (extra_libdir && extra_libdir[0])
     {
         length = strlen (extra_libdir) + 16 + 1;
diff --git a/src/core/wee-debug.c b/src/core/wee-debug.c
index 9dc9c2ec7..072f721fa 100644
--- a/src/core/wee-debug.c
+++ b/src/core/wee-debug.c
@@ -573,7 +573,7 @@ debug_directories ()
 {
     char *extra_libdir;
 
-    extra_libdir = getenv ("WEECHAT_EXTRA_LIBDIR");
+    extra_libdir = getenv (WEECHAT_EXTRA_LIBDIR);
 
     gui_chat_printf (NULL, "");
     gui_chat_printf (NULL, _("Directories:"));
diff --git a/src/core/wee-util.c b/src/core/wee-util.c
index d9cd4e2fe..bbffd7dcf 100644
--- a/src/core/wee-util.c
+++ b/src/core/wee-util.c
@@ -555,7 +555,7 @@ util_search_full_lib_name_ext (const char *filename, const char *extension,
               (strchr (filename, '.')) ? "" : extension);
 
     /* try libdir from environment variable WEECHAT_EXTRA_LIBDIR */
-    extra_libdir = getenv ("WEECHAT_EXTRA_LIBDIR");
+    extra_libdir = getenv (WEECHAT_EXTRA_LIBDIR);
     if (extra_libdir && extra_libdir[0])
     {
         length = strlen (extra_libdir) + strlen (name_with_ext) +
diff --git a/src/core/weechat.h b/src/core/weechat.h
index f53c26b21..f0e3785e4 100644
--- a/src/core/weechat.h
+++ b/src/core/weechat.h
@@ -93,6 +93,9 @@
 /* internal charset */
 #define WEECHAT_INTERNAL_CHARSET "UTF-8"
 
+/* name of environment variable with an extra lib dir */
+#define WEECHAT_EXTRA_LIBDIR "WEECHAT_EXTRA_LIBDIR"
+
 /* global variables and functions */
 extern int weechat_debug_core;
 extern char *weechat_argv0;
diff --git a/src/plugins/plugin.c b/src/plugins/plugin.c
index ac2009a1c..509f8d963 100644
--- a/src/plugins/plugin.c
+++ b/src/plugins/plugin.c
@@ -1041,7 +1041,7 @@ plugin_auto_load (int argc, char **argv,
     /* auto-load plugins in WEECHAT_EXTRA_LIBDIR environment variable */
     if (load_from_extra_lib_dir)
     {
-        extra_libdir = getenv ("WEECHAT_EXTRA_LIBDIR");
+        extra_libdir = getenv (WEECHAT_EXTRA_LIBDIR);
         if (extra_libdir && extra_libdir[0])
         {
             length = strlen (extra_libdir) + 16 + 1;