diff --git a/dust-lang/src/compiler.rs b/dust-lang/src/compiler.rs
index e01d10d..5a34c95 100644
--- a/dust-lang/src/compiler.rs
+++ b/dust-lang/src/compiler.rs
@@ -150,9 +150,7 @@ impl<'src> Compiler<'src> {
             .iter()
             .rev()
             .find_map(|(instruction, _, _)| {
-                let is_get_local = matches!(instruction.operation(), Operation::GetLocal);
-
-                if instruction.yields_value() && !is_get_local {
+                if instruction.yields_value() {
                     Some(instruction.a() + 1)
                 } else {
                     None
@@ -632,7 +630,11 @@ impl<'src> Compiler<'src> {
         let rule = ParseRule::from(&operator);
         let is_assignment = matches!(
             operator,
-            Token::PlusEqual | Token::MinusEqual | Token::StarEqual | Token::SlashEqual
+            Token::PlusEqual
+                | Token::MinusEqual
+                | Token::StarEqual
+                | Token::SlashEqual
+                | Token::PercentEqual
         );
 
         if push_back_left {
@@ -1729,7 +1731,7 @@ impl<'src> Compiler<'src> {
     ) -> Result<(), CompileError> {
         if matches!(
             (left, right),
-            (Type::Float, Type::Float) | (Type::Integer, Type::Integer)
+            (Type::Byte, Type::Byte) | (Type::Float, Type::Float) | (Type::Integer, Type::Integer)
         ) {
             Ok(())
         } else {
diff --git a/dust-lang/tests/math_add.rs b/dust-lang/tests/math_add.rs
index 8a99948..a95ea81 100644
--- a/dust-lang/tests/math_add.rs
+++ b/dust-lang/tests/math_add.rs
@@ -120,10 +120,7 @@ fn add_character_and_string() {
                 ),
                 (Instruction::r#return(true), Span(9, 9))
             ],
-            vec![
-                ConcreteValue::Character('a'),
-                ConcreteValue::String("b".to_string())
-            ],
+            vec![ConcreteValue::Character('a'), ConcreteValue::string("b")],
             vec![]
         ))
     );
@@ -287,8 +284,8 @@ fn add_strings() {
                 (Instruction::r#return(true), Span(20, 20))
             ],
             vec![
-                ConcreteValue::String("Hello, ".to_string()),
-                ConcreteValue::String("world!".to_string())
+                ConcreteValue::string("Hello, "),
+                ConcreteValue::string("world!")
             ],
             vec![]
         ))
@@ -327,8 +324,5 @@ fn add_string_and_character() {
         ))
     );
 
-    assert_eq!(
-        run(source),
-        Ok(Some(ConcreteValue::String("ab".to_string())))
-    );
+    assert_eq!(run(source), Ok(Some(ConcreteValue::string("ab"))));
 }
diff --git a/dust-lang/tests/math_divide.rs b/dust-lang/tests/math_divide.rs
index 8dfb1d2..f58eba4 100644
--- a/dust-lang/tests/math_divide.rs
+++ b/dust-lang/tests/math_divide.rs
@@ -18,9 +18,9 @@ fn divide_bytes() {
                     Instruction::divide(
                         Destination::Register(0),
                         Argument::Constant(0),
-                        Argument::Constant(0)
+                        Argument::Constant(1)
                     ),
-                    Span(0, 7)
+                    Span(5, 6)
                 ),
                 (Instruction::r#return(true), Span(11, 11))
             ],
diff --git a/dust-lang/tests/math_multiply.rs b/dust-lang/tests/math_multiply.rs
index 4436d95..8d53537 100644
--- a/dust-lang/tests/math_multiply.rs
+++ b/dust-lang/tests/math_multiply.rs
@@ -18,13 +18,13 @@ fn multiply_floats() {
                     Instruction::multiply(
                         Destination::Register(0),
                         Argument::Constant(0),
-                        Argument::Constant(1)
+                        Argument::Constant(0)
                     ),
                     Span(4, 5)
                 ),
                 (Instruction::r#return(true), Span(9, 9)),
             ],
-            vec![ConcreteValue::Float(2.0), ConcreteValue::Float(2.0)],
+            vec![ConcreteValue::Float(2.0)],
             vec![]
         ))
     );