diff --git a/src/eval.rs b/src/eval.rs
index 13a0cbd..d22d553 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,4 +1,4 @@
-pub fn do_math(arguments: &str, operator: char) -> u32 {
+pub fn do_math(arguments: String, operator: char) -> u32 {
     let split_args = arguments.split("-").collect::<Vec<&str>>();
 
     let num1: u32 = match split_args[0].parse() {
diff --git a/src/main.rs b/src/main.rs
index 8642199..f5ce187 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,10 +55,10 @@ impl Program {
 
         match opcode {
             'p' => println!("{}", self.args_or_vars(arguments)),
-            'a' => println!("{}", eval::do_math(arguments, '+')),
-            's' => println!("{}", eval::do_math(arguments, '-')),
-            'm' => println!("{}", eval::do_math(arguments, '*')),
-            'd' => println!("{}", eval::do_math(arguments, '/')),
+            'a' => println!("{}", eval::do_math(self.args_or_vars(arguments), '+')),
+            's' => println!("{}", eval::do_math(self.args_or_vars(arguments), '-')),
+            'm' => println!("{}", eval::do_math(self.args_or_vars(arguments), '*')),
+            'd' => println!("{}", eval::do_math(self.args_or_vars(arguments), '/')),
             'l' => self.add_var(arguments),
             _ => panic!("SyntaxError at opcode {}!", self.pc)
         }