diff --git a/rust/src/mlil/function.rs b/rust/src/mlil/function.rs
index 608d2507f..1c12b2c6b 100644
--- a/rust/src/mlil/function.rs
+++ b/rust/src/mlil/function.rs
@@ -137,7 +137,7 @@ impl MediumLevelILFunction {
         unsafe { BNDeleteUserVariable(self.get_function().handle, &var.raw()) }
     }
 
-    pub fn is_var_user_defined(self, var: &Variable) -> bool {
+    pub fn is_var_user_defined(&self, var: &Variable) -> bool {
         unsafe { BNIsVariableUserDefined(self.get_function().handle, &var.raw()) }
     }