diff --git a/src/bytecode/bytearray.hh b/src/bytecode/bytearray.hh
index 96e8311..d1906ad 100644
--- a/src/bytecode/bytearray.hh
+++ b/src/bytecode/bytearray.hh
@@ -39,7 +39,7 @@ public:
     [[nodiscard]] size_t size() const { return data_.size(); }
 
 private:
-    std::vector<uint8_t> data_;
+    std::vector<uint8_t> data_ {};
 };
 
 class BytecodeParsingError : public std::runtime_error {
diff --git a/src/bytecode/bytecodeprototype.hh b/src/bytecode/bytecodeprototype.hh
index e292589..682986e 100644
--- a/src/bytecode/bytecodeprototype.hh
+++ b/src/bytecode/bytecodeprototype.hh
@@ -13,9 +13,11 @@ struct BytecodePrototype {
     using Value = std::variant<int32_t, float>;
 
     struct Function {
-        uint16_t  n_pars = 0;
-        uint16_t  n_locals = 0;
-        ByteArray code {};
+        uint16_t  n_pars;
+        uint16_t  n_locals;
+        ByteArray code;
+
+        Function(uint16_t n_pars_, uint16_t n_locals_) : n_pars(n_pars_), n_locals(n_locals_), code(ByteArray {}) {}
     };
 
     std::vector<ConstantValue> constants {};
diff --git a/src/bytecode/tests.cc b/src/bytecode/tests.cc
index c4aeb7f..d5cb4e9 100644
--- a/src/bytecode/tests.cc
+++ b/src/bytecode/tests.cc
@@ -83,8 +83,8 @@ TEST(Bytecode, Code)
     f.code.append_byte(0x68);
     f.code.append_int(42);
 
-    f = bp.functions.emplace_back(2, 1);
-    f.code.append_byte(0x42);
+    auto& f2 = bp.functions.emplace_back(2, 1);
+    f2.code.append_byte(0x42);
 
     std::vector<uint8_t> expected = {
             // header