diff --git a/src/core/wee-eval.c b/src/core/wee-eval.c
index cdee2ec79..d008420ec 100644
--- a/src/core/wee-eval.c
+++ b/src/core/wee-eval.c
@@ -823,7 +823,9 @@ eval_expression (const char *expr, struct t_hashtable *pointers,
 {
     int condition, rc, pointers_allocated;
     char *value;
-    const char *prefix, *suffix, *default_prefix = "${", *default_suffix = "}";
+    const char *prefix, *suffix;
+    const char *default_prefix = EVAL_DEFAULT_PREFIX;
+    const char *default_suffix = EVAL_DEFAULT_SUFFIX;
     const char *ptr_value;
     struct t_gui_window *window;
 
diff --git a/src/core/wee-eval.h b/src/core/wee-eval.h
index 5f0ae7202..eb20e5192 100644
--- a/src/core/wee-eval.h
+++ b/src/core/wee-eval.h
@@ -20,8 +20,11 @@
 #ifndef WEECHAT_EVAL_H
 #define WEECHAT_EVAL_H 1
 
-#define EVAL_STR_FALSE "0"
-#define EVAL_STR_TRUE  "1"
+#define EVAL_STR_FALSE      "0"
+#define EVAL_STR_TRUE       "1"
+
+#define EVAL_DEFAULT_PREFIX "${"
+#define EVAL_DEFAULT_SUFFIX "}"
 
 struct t_hashtable;