diff --git a/libjlx/modules/ast.cppm b/libjlx/modules/ast.cppm
index 1db0d81..24a1a07 100644
--- a/libjlx/modules/ast.cppm
+++ b/libjlx/modules/ast.cppm
@@ -19,6 +19,7 @@ namespace jlx {
 		VariableDeclaration,
 		IfStatement,
 		ReturnStatement,
+		Assignment
 	};
 
 	export enum expression_type {
@@ -96,6 +97,19 @@ namespace jlx {
 		~return_statement() override = default;
 	};
 
+	export struct assignment : public statement {
+		explicit assignment(const token& t): statement(Assignment, t) {
+
+		}
+
+		assignment(std::unique_ptr<expression> target, std::unique_ptr<expression> value, const token& t) : statement(Assignment, t), target(std::move(target)), value(std::move(value)) {
+
+		}
+
+		std::unique_ptr<expression> target;
+		std::unique_ptr<expression> value;
+	};
+
 	export struct block : public statement {
 		explicit block(const token& t) : statement(Block, t) {
 
@@ -611,6 +625,35 @@ namespace jlx {
 			return current->content;
 		}
 
+		std::unique_ptr<statement> parse_assignment() {
+			auto& start = *current;
+
+			auto ptr = current;
+
+			if (ptr->type != Identifier) {
+				fail_invalid_token(*current);
+			}
+
+			auto target = std::make_unique<identifier_expression>(start, start.content);
+
+			++ptr;
+
+			if (ptr == last) {
+				return nullptr;
+			}
+
+			if (ptr->type != Operator && ptr->content != "=") {
+				return nullptr;
+			}
+
+			next();
+			next();
+
+			auto expr = parse_expression();
+
+			return std::make_unique<assignment>(std::move(target), std::move(expr), start);
+		}
+
 		std::unique_ptr<statement> parse_statement(bool top_level = false) {
 			if (current == last) {
 				return nullptr;
@@ -628,6 +671,13 @@ namespace jlx {
 				}
 			}
 
+			if (current->type == token_type::Identifier) {
+				auto res = parse_assignment();
+				if (res != nullptr) {
+					return res;
+				}
+			}
+
 			return parse_expression();
 		}
 
diff --git a/libjlx/modules/interpreter.cppm b/libjlx/modules/interpreter.cppm
index 00644f8..eabecc2 100644
--- a/libjlx/modules/interpreter.cppm
+++ b/libjlx/modules/interpreter.cppm
@@ -9,6 +9,8 @@ module;
 #include <ranges>
 #include <format>
 #include <iostream>
+#include <functional>
+#include <memory>
 
 export module jlx:interpreter;
 import :ast;
@@ -17,6 +19,12 @@ import :type_checker;
 namespace jlx {
 	using runtime_value = std::variant<std::string, int8_t, int16_t, int32_t, int64_t, uint8_t, uint16_t, uint32_t, uint64_t, float, double, bool>;
 
+	enum class set_result {
+		success,
+		constant,
+		not_found
+	};
+
 	struct interpreter_variable {
 		std::string type;
 		bool writable;
@@ -52,6 +60,9 @@ namespace jlx {
 		virtual interpreter_variable_scope& current_variable_scope() = 0;
 		virtual bool is_in_function() = 0;
 		virtual void inject_value(const std::string_view&, runtime_value) = 0;
+		virtual set_result set_value(const std::string_view&, runtime_value) = 0;
+
+		virtual runtime_value type_cast(const std::string_view&, const runtime_value&) = 0;
 
 		virtual ~base_interpreter() = default;
 	};
@@ -383,7 +394,7 @@ namespace jlx {
 			auto* lv = dynamic_cast<const literal_value*>(&e);
 
 			if (lv == nullptr) {
-				throw interpreter_error("Internal interpreter error", e.t);
+				throw interpreter_error("Internal interpreter error #0", e.t);
 			}
 
 			auto& content = lv->t.content;
@@ -576,7 +587,7 @@ namespace jlx {
 						auto* svo = dynamic_cast<const single_operation*>(&e);
 
 						if (svo == nullptr) {
-							throw interpreter_error("Internal interpreter error", e.t);
+							throw interpreter_error("Internal interpreter error #1", e.t);
 						}
 
 						auto val = eval_expression(*svo->operand);
@@ -604,7 +615,7 @@ namespace jlx {
 						auto* dvo = dynamic_cast<const dual_operation*>(&e);
 
 						if (dvo == nullptr) {
-							throw interpreter_error("Internal interpreter error", e.t);
+							throw interpreter_error("Internal interpreter error #2", e.t);
 						}
 
 						if (dvo->operator_token.content == "||") {
@@ -637,7 +648,7 @@ namespace jlx {
 						auto* call = dynamic_cast<const function_call*>(&e);
 
 						if (call == nullptr) {
-							throw interpreter_error("Internal interpreter error", e.t);
+							throw interpreter_error("Internal interpreter error #3", e.t);
 						}
 
 						auto it = functions.find(call->function_name);
@@ -652,7 +663,7 @@ namespace jlx {
 							auto arg = eval_expression(*a);
 
 							if (!arg.has_value()) {
-								throw interpreter_error("Internal interpreter error", a->t);
+								throw interpreter_error("Internal interpreter error #4", a->t);
 							}
 							args.emplace_back(arg.value());
 						}
@@ -664,7 +675,7 @@ namespace jlx {
 						auto* id = dynamic_cast<const identifier_expression*>(&e);
 
 						if (id == nullptr) {
-							throw interpreter_error("Internal interpreter error", e.t);
+							throw interpreter_error("Internal interpreter error #5", e.t);
 						}
 
 						for (auto& s : std::ranges::reverse_view(scopes)) {
@@ -680,13 +691,111 @@ namespace jlx {
 			}
 		}
 
+		runtime_value type_cast(const std::string_view& target_type, const runtime_value& value) override {
+			auto src_type = get_type_for_value(value);
+
+			if (src_type == target_type) {
+				return value;
+			}
+
+			if (!type_checker_utils::is_convertible_to(src_type, target_type)) {
+				throw std::runtime_error(std::format("Cannot convert '{}' to '{}'", src_type, target_type).c_str());
+			}
+
+			if (target_type == "u16") {
+				if (src_type == "u8") {
+					return static_cast<uint16_t>(std::get<uint8_t>(value));
+				}
+			}
+			if (target_type == "i16") {
+				if (src_type == "u8") {
+					return static_cast<int16_t>(std::get<uint8_t>(value));
+				}
+
+				if (src_type == "i8") {
+					return static_cast<int16_t>(std::get<int8_t>(value));
+				}
+			}
+			if (target_type == "u32") {
+				if (src_type == "u8") {
+					return static_cast<uint32_t>(std::get<uint8_t>(value));
+				}
+
+				if (src_type == "u16") {
+					return static_cast<uint32_t>(std::get<uint16_t>(value));
+				}
+			}
+			if (target_type == "i32") {
+				if (src_type == "u8") {
+					return static_cast<int32_t>(std::get<uint8_t>(value));
+				}
+
+				if (src_type == "u16") {
+					return static_cast<int32_t>(std::get<uint16_t>(value));
+				}
+
+				if (src_type == "i8") {
+					return static_cast<int32_t>(std::get<int8_t>(value));
+				}
+
+				if (src_type == "i16") {
+					return static_cast<int32_t>(std::get<int16_t>(value));
+				}
+			}
+			if (target_type == "u64") {
+				if (src_type == "u8") {
+					return static_cast<uint64_t>(std::get<uint8_t>(value));
+				}
+
+				if (src_type == "u16") {
+					return static_cast<uint64_t>(std::get<uint16_t>(value));
+				}
+
+				if (src_type == "u32") {
+					return static_cast<uint64_t>(std::get<uint32_t>(value));
+				}
+			}
+			if (target_type == "i64") {
+				if (src_type == "u8") {
+					return static_cast<int64_t>(std::get<uint8_t>(value));
+				}
+
+				if (src_type == "u16") {
+					return static_cast<int64_t>(std::get<uint16_t>(value));
+				}
+
+				if (src_type == "u32") {
+					return static_cast<int64_t>(std::get<uint32_t>(value));
+				}
+
+				if (src_type == "i8") {
+					return static_cast<int64_t>(std::get<int8_t>(value));
+				}
+
+				if (src_type == "i16") {
+					return static_cast<int64_t>(std::get<int16_t>(value));
+				}
+				
+				if (src_type == "i32") {
+					return static_cast<int64_t>(std::get<int32_t>(value));
+				}
+			}
+			if (target_type == "f64") {
+				if (src_type == "f32") {
+					return static_cast<double>(std::get<float>(value));
+				}
+			}
+
+			throw std::runtime_error(std::format("Conversion from '{}' to '{}' not implemented", src_type, target_type).c_str());
+		}
+
 		std::optional<runtime_value> execute_statement(const statement& s) override {
 			switch (s.type) {
 				case Expression: {
 						auto* ex = dynamic_cast<const expression*>(&s);
 
 						if (ex == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #6", s.t);
 						}
 
 						return eval_expression(*ex);
@@ -696,7 +805,7 @@ namespace jlx {
 						auto* b = dynamic_cast<const block*>(&s);
 
 						if (b == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #7", s.t);
 						}
 
 						push_variable_scope();
@@ -721,7 +830,7 @@ namespace jlx {
 						auto* r = dynamic_cast<const return_statement*>(&s);
 
 						if (r == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #8", s.t);
 						}
 
 						auto val = r->expression != nullptr ? eval_expression(*r->expression) : std::nullopt;
@@ -735,7 +844,7 @@ namespace jlx {
 						auto* r = dynamic_cast<const root_statement*>(&s);
 
 						if (r == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #9", s.t);
 						}
 
 						for (auto& st : r->statements) {
@@ -747,7 +856,7 @@ namespace jlx {
 						auto* d = dynamic_cast<const function_declaration*>(&s);
 
 						if (d == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #10", s.t);
 						}
 
 						if (functions.find(d->name) != functions.end()) {
@@ -763,7 +872,7 @@ namespace jlx {
 						auto* d = dynamic_cast<const variable_declaration*>(&s);
 
 						if (d == nullptr) {
-							throw interpreter_error("Internal interpreter error", s.t);
+							throw interpreter_error("Internal interpreter error #11", s.t);
 						}
 
 						auto& sc = current_variable_scope();
@@ -775,7 +884,7 @@ namespace jlx {
 						auto val = d->initial_expression != nullptr ? eval_expression(*d->initial_expression) : throw std::runtime_error("Non-initialized variables are not supported yet."); //TODO: This
 
 						sc.variables.insert_or_assign(d->name, interpreter_variable {
-							d->type.has_value() ? d->type.value() : "void",
+							d->type.has_value() ? d->type.value() :  (val.has_value() ? std::string(get_type_for_value(val.value())) : "void"),
 							!d->constant,
 							val.has_value() ? val.value() : runtime_value(0),
 						});
@@ -787,7 +896,7 @@ namespace jlx {
 					auto* is = dynamic_cast<const if_statement*>(&s);
 
 					if (is == nullptr) {
-						throw interpreter_error("Internal interpreter error", s.t);
+						throw interpreter_error("Internal interpreter errori #12", s.t);
 					}
 
 					auto condition = eval_expression(*is->condition);
@@ -803,9 +912,43 @@ namespace jlx {
 					if (std::get<11>(condition.value())) {
 						execute_statement(*is->block);
 					}
+
+					return std::nullopt;
+				} break;
+				case Assignment: {
+					auto* as = dynamic_cast<const assignment*>(&s);
+
+					if (as == nullptr) {
+						throw interpreter_error("Internal interpreter error #13", s.t);
+					}
+
+					auto* target = dynamic_cast<const identifier_expression*>(as->target.get());
+
+					if (target == nullptr) {
+						throw interpreter_error("Invalid target expression for assignment", as->target->t);
+					}
+
+					auto& name = target->name;
+
+					auto val = eval_expression(*as->value);
+
+					if (!val.has_value()) {
+						throw interpreter_error("Assignment with no value", as->value->t);
+					}
+
+					auto set_res = set_value(name, val.value());
+
+					switch (set_res) {
+						case set_result::constant:
+							throw interpreter_error(std::format("Cannot assign to constant value '{}'", name), as->t);
+						case set_result::not_found:
+							throw interpreter_error(std::format("Symbol '{}' not found", name), as->t);
+						default:
+							return std::nullopt;
+					}
 				} break;
 			}
-			throw interpreter_error("Internal interpreter error", s.t);
+			throw interpreter_error("Internal interpreter error #14", s.t);
 		}
 
 		void push_variable_scope() override {
@@ -840,9 +983,24 @@ namespace jlx {
 			});
 		}
 
+		set_result set_value(const std::string_view& name, runtime_value val) override {
+			for(auto& v : std::ranges::reverse_view(scopes)) {
+				auto it = v.variables.find(std::string(name));
+				if (it != v.variables.end()) {
+					if (it->second.writable) {
+						it->second.value = type_cast(it->second.type, val);
+						return set_result::success;
+					}
+					return set_result::constant;
+				}
+			}
+
+			return set_result::not_found;
+		}
+
 		interpreter_function_scope& current_function_scope() override {
 			if (function_scopes.empty()) {
-				throw std::runtime_error("Internal interpreter error");
+				throw std::runtime_error("Internal interpreter error #15");
 			}
 
 			return function_scopes.back();
@@ -856,4 +1014,4 @@ namespace jlx {
 			return !function_scopes.empty();
 		}
 	};
-}
\ No newline at end of file
+}
diff --git a/libjlx/modules/type_checker.cppm b/libjlx/modules/type_checker.cppm
index 1722614..f2e8828 100644
--- a/libjlx/modules/type_checker.cppm
+++ b/libjlx/modules/type_checker.cppm
@@ -6,6 +6,8 @@ module;
 #include <string>
 #include <string_view>
 #include <algorithm>
+#include <memory>
+#include <unordered_map>
 
 export module jlx:type_checker;
 
@@ -466,11 +468,11 @@ namespace jlx {
 						}
 
 
-					if (type == "comptime_int") {
-						type = "i64";
-					} else if (type == "comptime_float") {
-						type = "f64";
-					}
+						if (type == "comptime_int") {
+							type = "i64";
+						} else if (type == "comptime_float") {
+							type = "f64";
+						}
 
 						if (!type.has_value()) {
 							throw std::runtime_error("Cannot infer variable declaration type");
@@ -533,6 +535,22 @@ namespace jlx {
 						}
 					}
 					break;
+				case Assignment: {
+						auto* as = dynamic_cast<assignment*>(&s);
+
+						if (!as->target->evaluated_type.has_value()) {
+							type_checker_utils::evaluate_expression_type(*as->target, *this);
+						}
+
+						if (!as->value->evaluated_type.has_value()) {
+							type_checker_utils::evaluate_expression_type(*as->value, *this);
+						}
+
+						if (!type_checker_utils::is_convertible_to(as->value->evaluated_type.value(), as->target->evaluated_type.value())) {
+							throw type_error(as->target->t, as->value->evaluated_type.value());
+						}
+					}
+					break;
 			}
 		}
 
@@ -614,4 +632,4 @@ namespace jlx {
 			});
 		}
 	};
-}
\ No newline at end of file
+}