diff --git a/src/assembler/assembler.cc b/src/assembler/assembler.cc
index f5fe59f..d189a26 100644
--- a/src/assembler/assembler.cc
+++ b/src/assembler/assembler.cc
@@ -31,6 +31,8 @@ ByteArray Assembler::assemble()
             } else if (std::get<std::string>(t.token) == ".func") {
                 section = Section::Function;
                 function_id = std::get<int>(expect_token(TokenType::Integer));
+                if (function_id >= bp.functions.size())
+                    bp.functions.resize(function_id + 1, { 0, 0 });
                 expect_token(TokenType::Enter);
             } else {
                 throw AssemblyError("Invalid directive " + std::get<std::string>(t.token), t.line, t.column);
diff --git a/src/bytecode/bytecodeprototype.hh b/src/bytecode/bytecodeprototype.hh
index df92c81..5a1bb58 100644
--- a/src/bytecode/bytecodeprototype.hh
+++ b/src/bytecode/bytecodeprototype.hh
@@ -14,7 +14,7 @@ struct BytecodePrototype {
     struct Function {
         uint16_t  n_pars;
         uint16_t  n_locals;
-        ByteArray code;
+        ByteArray code {};
 
         Function(uint16_t n_pars_, uint16_t n_locals_) : n_pars(n_pars_), n_locals(n_locals_), code(ByteArray {}) {}
     };