diff --git a/libs/parser/rules/pslang.y b/libs/parser/rules/pslang.y
index c256dbf..687b513 100644
--- a/libs/parser/rules/pslang.y
+++ b/libs/parser/rules/pslang.y
@@ -155,6 +155,7 @@ template <typename T>
 %token end 0
 
 %right arrow
+%nonassoc mut
 %left ampersand double_ampersand vertical_bar double_vertical_bar circumflex
 %left equals not_equals less greater less_equals greater_equals
 %nonassoc as