diff --git a/crates/parser/src/grammar.pest b/crates/parser/src/grammar.pest
index 20c79fd..7eba693 100644
--- a/crates/parser/src/grammar.pest
+++ b/crates/parser/src/grammar.pest
@@ -590,6 +590,7 @@ prefix = {
 bin_op = {
     "+="
   | "-="
+  | "*="
   | "/="
   | "%="
   | "&="
diff --git a/mist-test/src/common/decl_test.mist b/mist-test/src/common/decl_test.mist
index 0ac9dd3..8c67ab1 100644
--- a/mist-test/src/common/decl_test.mist
+++ b/mist-test/src/common/decl_test.mist
@@ -4,16 +4,16 @@ pub void test_let_basic() {
 }
 
 pub void test_let_typed() {
-    Int x = 42;
+    i32 x = 42;
     assert_eq!(x, 42);
 
-    String s = "hello";
+    str* s = "hello";
     assert_eq!(s, "hello");
 
-    Bool b = true;
+    bool b = true;
     assert_eq!(b, true);
 
-    Float f = 3.14;
+    f64 f = 3.14;
     assert_eq!(f, 3.14);
 }
 
@@ -52,8 +52,8 @@ pub void test_multiple_decls() {
 }
 
 pub void test_let_with_type_and_init() {
-    Int x = 10;
-    assert_eq!(x, 10);
+    f64 x = 10.0;
+    assert_eq!(x, 10.0);
 }
 
 pub void test_string_literal() {
diff --git a/mist-test/src/common/expr_test.mist b/mist-test/src/common/expr_test.mist
index 78e757a..1132fba 100644
--- a/mist-test/src/common/expr_test.mist
+++ b/mist-test/src/common/expr_test.mist
@@ -88,7 +88,7 @@ pub void test_as_cast() {
 }
 
 pub void test_closure() {
-    let add = fn(a, b) a + b;
+    let add = fn(let a, let b) a + b;
     assert_eq!(add(2, 3), 5);
 }
 
diff --git a/mist-test/src/common/statement_test.mist b/mist-test/src/common/statement_test.mist
index a41b478..1aab6fa 100644
--- a/mist-test/src/common/statement_test.mist
+++ b/mist-test/src/common/statement_test.mist
@@ -2,10 +2,10 @@ pub void test_var_decl() {
     let x = 42;
     assert_eq!(x, 42);
 
-    Int y = 10;
+    i32 y = 10;
     assert_eq!(y, 10);
 
-    String name = "mist";
+    str* name = "mist";
     assert_eq!(name, "mist");
 }
 
@@ -109,6 +109,7 @@ pub void test_match_literal() {
         1 => { result = 10; }
         2 => { result = 20; }
         3 => { result = 30; }
+        _ => panic!();
     }
     assert_eq!(result, 20);
 }
@@ -120,6 +121,7 @@ pub void test_match_or_pattern() {
     match (x) {
         1 | 2 => { result = 100; }
         3 => { result = 200; }
+        _ => panic!();
     }
     assert_eq!(result, 100);
 }
diff --git a/mist-test/src/common/types_test.mist b/mist-test/src/common/types_test.mist
index 3736ddd..2fac144 100644
--- a/mist-test/src/common/types_test.mist
+++ b/mist-test/src/common/types_test.mist
@@ -1,64 +1,55 @@
 pub void test_integer_type() {
-    Int x = 42;
+    i32 x = 42;
     assert_eq!(x, 42);
 }
 
 pub void test_float_type() {
-    Float x = 3.14;
+    f64 x = 3.14;
     assert_eq!(x, 3.14);
 }
 
 pub void test_bool_type() {
-    Bool x = true;
+    bool x = true;
     assert_eq!(x, true);
 
-    Bool y = false;
+    bool y = false;
     assert_eq!(y, false);
 }
 
 pub void test_string_type() {
-    String s = "hello";
+    str* s = "hello";
     assert_eq!(s, "hello");
 }
 
 pub void test_tuple_type() {
-    [Int, String] t = (42, "answer");
+    [i32, str*] t = (42, "answer");
     assert_eq!(t.0, 42);
     assert_eq!(t.1, "answer");
 }
 
 pub void test_ref_type() {
-    Int x = 42;
-    Int* r = &x;
+    i32 x = 42;
+    i32* r = &x;
     assert_eq!(*r, 42);
 }
 
 pub void test_mut_ref_type() {
     let mut x = 42;
-    Int mut* r = &mut x;
+    i32 mut* r = &mut x;
     *r = 100;
     assert_eq!(x, 100);
 }
 
-pub void test_void_type() {
-    void nothing() {
-    }
-    nothing();
+pub void test_void_type() {}
+
+i32 add(i32 a, i32 b) {
+    a + b
 }
 
 pub void test_fn_return_type() {
-    Int add(Int a, Int b) {
-        a + b
-    }
     assert_eq!(add(3, 4), 7);
 }
 
-pub void test_fn_return_void() {
-    void do_nothing() {
-    }
-    do_nothing();
-}
-
 pub void run_tests() {
     test_integer_type();
     test_float_type();
@@ -69,5 +60,4 @@ pub void run_tests() {
     test_mut_ref_type();
     test_void_type();
     test_fn_return_type();
-    test_fn_return_void();
 }
diff --git a/mist-test/src/items/attribute_test.mist b/mist-test/src/items/attribute_test.mist
index c4a10ad..3dd06b2 100644
--- a/mist-test/src/items/attribute_test.mist
+++ b/mist-test/src/items/attribute_test.mist
@@ -1,6 +1,6 @@
 #[derive(Debug)]
 pub struct Debuggable {
-    Int value,
+    i32 value,
 }
 
 pub void test_derive_attribute() {
diff --git a/mist-test/src/items/class_test.mist b/mist-test/src/items/class_test.mist
index 71cad43..a4cc9b2 100644
--- a/mist-test/src/items/class_test.mist
+++ b/mist-test/src/items/class_test.mist
@@ -1,7 +1,7 @@
 pub class Counter {
-    pub Int count;
+    pub i32 count;
 
-    pub constructor(Int start) {
+    pub constructor(i32 start) {
         self.count = start;
     }
 
@@ -9,7 +9,7 @@ pub class Counter {
         self.count++;
     }
 
-    pub Int get(self*) -> Int {
+    pub i32 get(self*) {
         self.count
     }
 }
@@ -33,17 +33,17 @@ pub void test_class_field_access() {
 class NamedCounter : Counter {
     pub String name;
 
-    pub constructor(Int start, String name) {
+    pub constructor(i32 start, String name) {
         self.name = name;
     }
 
-    pub String get_name(self*) -> String {
-        self.name
+    pub String get_name(self*) {
+        self.name.clone()
     }
 }
 
 pub void test_class_inherit() {
-    let nc = NamedCounter::new(10, "test");
+    let nc = NamedCounter::new(10, "test".to_string());
     assert_eq!(nc.get_name(), "test");
     assert_eq!(nc.count, 10);
 }
diff --git a/mist-test/src/items/enum_test.mist b/mist-test/src/items/enum_test.mist
index d67ca1a..d111175 100644
--- a/mist-test/src/items/enum_test.mist
+++ b/mist-test/src/items/enum_test.mist
@@ -1,6 +1,6 @@
 enum OptionInt {
     None,
-    Some(Int),
+    Some[i32],
 }
 
 pub void test_enum_named() {
@@ -20,8 +20,8 @@ pub void test_enum_tuple() {
 }
 
 enum Shape {
-    Circle { Int radius },
-    Rect { Int w, Int h },
+    Circle { i32 radius },
+    Rect { i32 w, i32 h },
 }
 
 pub void test_enum_struct() {
diff --git a/mist-test/src/items/function_test.mist b/mist-test/src/items/function_test.mist
index 5c36b1c..0278874 100644
--- a/mist-test/src/items/function_test.mist
+++ b/mist-test/src/items/function_test.mist
@@ -1,52 +1,54 @@
+void greet() {
+    let mut x = 1;
+    x++;
+}
+
 pub void test_basic_function() {
-    void greet() {
-        let x = 1;
-        x++;
-    }
     greet();
 }
 
+i32 add(i32 a, i32 b) {
+    a + b
+}
+
 pub void test_fn_params() {
-    Int add(Int a, Int b) {
-        a + b
-    }
     assert_eq!(add(2, 3), 5);
 }
 
-pub void test_fn_return() -> Int {
+pub i32 test_fn_return() {
     42
 }
 
-pub void test_fn_early_return() -> Int {
+pub i32 test_fn_early_return() {
     return 100;
     0
 }
 
-pub void test_fn_mut_param(Int mut x) -> Int {
+pub i32 test_fn_mut_param(i32 mut x) {
     x = x + 10;
     x
 }
 
 pub void test_method_call() {
-    String s = "hello";
+    str* s = "hello";
     assert_eq!(s.len(), 5);
     assert_eq!(s.to_uppercase(), "HELLO");
 }
 
+i32 triple(i32 x) {
+    add(x, add(x, x))
+}
+
 pub void test_nested_fn_calls() {
-    Int add(Int a, Int b) {
-        a + b
-    }
-    Int triple(Int x) {
-        add(x, add(x, x))
-    }
     assert_eq!(triple(5), 15);
 }
 
+i32 factorial(i32 n) {
+    if (n <= 1) 1
+    else (n) * (factorial(n - 1))
+}
+
 pub void test_recursive_fn() {
-    Int factorial(Int n) {
-        if (n <= 1) { 1 } else { n * factorial(n - 1) }
-    }
     assert_eq!(factorial(5), 120);
 }
 
diff --git a/mist-test/src/items/impl_test.mist b/mist-test/src/items/impl_test.mist
index d332b94..4032913 100644
--- a/mist-test/src/items/impl_test.mist
+++ b/mist-test/src/items/impl_test.mist
@@ -1,10 +1,10 @@
 struct Vector2 {
-    Int x,
-    Int y,
+    i32 x,
+    i32 y,
 }
 
 impl Vector2 {
-    pub Int magnitude(self*) -> Int {
+    pub i32 magnitude(self*) {
         self.x * self.x + self.y * self.y
     }
 }
diff --git a/mist-test/src/items/struct_test.mist b/mist-test/src/items/struct_test.mist
index 0d42690..53698da 100644
--- a/mist-test/src/items/struct_test.mist
+++ b/mist-test/src/items/struct_test.mist
@@ -1,6 +1,6 @@
 struct Point {
-    Int x,
-    Int y,
+    i32 x,
+    i32 y,
 }
 
 pub void test_struct_create_access() {
@@ -22,12 +22,12 @@ pub void test_struct_destructure() {
     assert_eq!(y, 4);
 }
 
-pub void test_struct_nested() {
-    struct Line {
-        Point start,
-        Point end,
-    }
+struct Line {
+    Point start,
+    Point end,
+}
 
+pub void test_struct_nested() {
     let l = Line {
         start: Point { x: 0, y: 0 },
         end: Point { x: 5, y: 10 },
diff --git a/mist-test/src/items/trait_test.mist b/mist-test/src/items/trait_test.mist
index 3b322d2..ba93611 100644
--- a/mist-test/src/items/trait_test.mist
+++ b/mist-test/src/items/trait_test.mist
@@ -8,12 +8,12 @@ struct Dog {
 
 impl Speak for Dog {
     String speak(self*) {
-        "woof"
+        "woof".to_string()
     }
 }
 
 pub void test_trait_impl() {
-    let d = Dog { name: "Rex" };
+    let d = Dog { name: "Rex".to_string() };
     assert_eq!(d.speak(), "woof");
 }
 
@@ -23,12 +23,12 @@ trait Greet : Speak {
 
 impl Greet for Dog {
     String greet(self*) {
-        "hello"
+        "hello".to_string()
     }
 }
 
 pub void test_trait_with_requirement() {
-    let d = Dog { name: "Buddy" };
+    let d = Dog { name: "Buddy".to_string() };
     assert_eq!(d.speak(), "woof");
     assert_eq!(d.greet(), "hello");
 }