diff --git a/flake.nix b/flake.nix
index a6ce5fce..79b1fa63 100644
--- a/flake.nix
+++ b/flake.nix
@@ -163,7 +163,10 @@
           clippy
           pre-commit
           rustfmt
+          rust-analyzer
         ];
+        # https://nixos.wiki/wiki/Rust#Shell.nix_example
+        RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";
       };
       devShells.x86_64-linux.msys2 = pkgs.mkShell {
         name = "nac3-dev-shell-msys2";
diff --git a/nac3core/irrt/irrt/error_context.hpp b/nac3core/irrt/irrt/error_context.hpp
new file mode 100644
index 00000000..c1dfa6ec
--- /dev/null
+++ b/nac3core/irrt/irrt/error_context.hpp
@@ -0,0 +1,69 @@
+#pragma once
+
+#include "int_defs.hpp"
+#include "utils.hpp"
+
+namespace {
+// nac3core's "str" struct type definition
+template <typename SizeT>
+struct Str {
+    const char* content;
+    SizeT length;
+};
+
+struct ErrorContext {
+    const char* message_template; // MUST BE `&'static`
+    uint64_t param1;
+    uint64_t param2;
+    uint64_t param3;
+
+    void initialize() {
+        clear_error();
+    }
+
+    void clear_error() {
+        // Point the message_template to an empty str. Don't set it to nullptr as a sentinel
+        set_error("");
+    }
+
+    void set_error(const char* message, uint64_t param1 = 0, uint64_t param2 = 0, uint64_t param3 = 0) {
+        this->message_template = message;
+        this->param1 = param1;
+        this->param2 = param2;
+        this->param3 = param3;
+    }
+
+    bool has_error() {
+        return !cstr_utils::is_empty(message_template);
+    }
+
+    template <typename SizeT>
+    void set_error_str(Str<SizeT> *dst_str) {
+        dst_str->content = message_template;
+        dst_str->length = (SizeT) cstr_utils::length(message_template);
+    }
+};
+}
+
+extern "C" {
+
+void __nac3_error_context_initialize(ErrorContext* errctx) {
+    errctx->initialize();
+}
+
+uint8_t __nac3_error_context_has_no_error(ErrorContext* errctx) {
+    return !errctx->has_error();
+}
+
+void __nac3_error_context_get_error_str(ErrorContext* errctx, Str<int32_t> *dst_str) {
+    errctx->set_error_str<int32_t>(dst_str);
+}
+
+void __nac3_error_context_get_error_str64(ErrorContext* errctx, Str<int64_t> *dst_str) {
+    errctx->set_error_str<int64_t>(dst_str);
+}
+
+void __nac3_error_dummy_raise(ErrorContext* errctx) {
+    errctx->set_error("THROWN FROM __nac3_error_dummy_raise!!!!!!");
+}
+}
\ No newline at end of file
diff --git a/nac3core/irrt/irrt/string_utils.hpp b/nac3core/irrt/irrt/string_utils.hpp
new file mode 100644
index 00000000..c2750600
--- /dev/null
+++ b/nac3core/irrt/irrt/string_utils.hpp
@@ -0,0 +1,60 @@
+#pragma once
+
+#include "int_defs.hpp"
+
+namespace {
+namespace string {
+    bool is_empty(const char* str) {
+        return str[0] == '\0';
+    }
+
+    int8_t compare(const char* a, const char* b) {
+        uint32_t i = 0;
+        while (true) {
+            if (a[i] < b[i]) {
+                return -1;
+            } else if (a[i] > b[i]) {
+                return 1;
+            } else { // a[i] == b[i]
+                if (a[i] == '\0') {
+                    return 0;
+                } else {
+                    continue;
+                }
+            }
+        }
+    }
+
+    int8_t equal(const char* a, const char* b) {
+        return compare(a, b) == 0;
+    }
+
+    uint32_t length(const char* str) {
+        uint32_t length = 0;
+        while (*str != '\0') {
+            length++;
+            str++;
+        }
+        return length;
+    }
+
+    bool copy(const char* src, char* dst, uint32_t dst_max_size) {
+        for (uint32_t i = 0; i < dst_max_size; i++) {
+            bool is_last = i + 1 == dst_max_size;
+            if (is_last && src[i] != '\0') {
+                dst[i] = '\0';
+                return false;
+            }
+
+            if (src[i] == '\0') {
+                dst[i] = '\0';
+                return true;
+            }
+
+            dst[i] = src[i];
+        }
+
+        __builtin_unreachable();
+    }
+}
+}
\ No newline at end of file
diff --git a/nac3core/irrt/irrt/utils.hpp b/nac3core/irrt/irrt/utils.hpp
index 6735f36b..27dcbb6e 100644
--- a/nac3core/irrt/irrt/utils.hpp
+++ b/nac3core/irrt/irrt/utils.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "int_defs.hpp"
+
 namespace {
 template <typename T>
 const T& max(const T& a, const T& b) {
@@ -18,4 +20,69 @@ bool arrays_match(int len, T* as, T* bs) {
     }
     return true;
 }
+
+template<typename T>
+uint32_t int_log_floor(T value, T base) {
+    uint32_t result = 0;
+    while (value >= base) {
+        result++;
+        value /= base;
+    }
+    return result;
+}
+
+namespace cstr_utils {
+    bool is_empty(const char* str) {
+        return str[0] == '\0';
+    }
+
+    int8_t compare(const char* a, const char* b) {
+        uint32_t i = 0;
+        while (true) {
+            if (a[i] < b[i]) {
+                return -1;
+            } else if (a[i] > b[i]) {
+                return 1;
+            } else { // a[i] == b[i] 
+                if (a[i] == '\0') {
+                    return 0;
+                } else {
+                    i++;
+                }
+            }
+        }
+    }
+
+    int8_t equal(const char* a, const char* b) {
+        return compare(a, b) == 0;
+    }
+
+    uint32_t length(const char* str) {
+        uint32_t length = 0;
+        while (*str != '\0') {
+            length++;
+            str++;
+        }
+        return length;
+    }
+
+    bool copy(const char* src, char* dst, uint32_t dst_max_size) {
+        for (uint32_t i = 0; i < dst_max_size; i++) {
+            bool is_last = i + 1 == dst_max_size;
+            if (is_last && src[i] != '\0') {
+                dst[i] = '\0';
+                return false;
+            }
+
+            if (src[i] == '\0') {
+                dst[i] = '\0';
+                return true;
+            }
+
+            dst[i] = src[i];
+        }
+
+        __builtin_unreachable();
+    }
+}
 }
\ No newline at end of file
diff --git a/nac3core/irrt/irrt_everything.hpp b/nac3core/irrt/irrt_everything.hpp
index 63e3e63a..5abbf61f 100644
--- a/nac3core/irrt/irrt_everything.hpp
+++ b/nac3core/irrt/irrt_everything.hpp
@@ -1,3 +1,6 @@
+#pragma once
+
 #include "irrt/core.hpp"
+#include "irrt/error_context.hpp"
 #include "irrt/int_defs.hpp"
 #include "irrt/utils.hpp"
\ No newline at end of file
diff --git a/nac3core/irrt/irrt_test.cpp b/nac3core/irrt/irrt_test.cpp
index 8aa64c2f..57cdd3e8 100644
--- a/nac3core/irrt/irrt_test.cpp
+++ b/nac3core/irrt/irrt_test.cpp
@@ -9,8 +9,11 @@
 
 #include "test/core.hpp"
 #include "test/test_core.hpp"
+#include "test/test_utils.hpp"
 
 int main() {
-    test_int_exp();
+    run_test_core();
+    run_test_print();
+    run_test_utils();
     return 0;
 }
\ No newline at end of file
diff --git a/nac3core/irrt/test/print.hpp b/nac3core/irrt/test/print.hpp
index bd0ec746..9fd92ff7 100644
--- a/nac3core/irrt/test/print.hpp
+++ b/nac3core/irrt/test/print.hpp
@@ -4,39 +4,39 @@
 #include <cstdio>
 
 template <class T>
-void print_value(const T& value) {}
+void print_value(T value);
 
 template <>
-void print_value(const int8_t& value) {
+void print_value(char value) {
+    printf("'%c' (ord=%d)", value, value);
+}
+
+template <>
+void print_value(int8_t value) {
     printf("%d", value);
 }
 
 template <>
-void print_value(const int32_t& value) {
+void print_value(int32_t value) {
     printf("%d", value);
 }
 
 template <>
-void print_value(const uint8_t& value) {
+void print_value(uint8_t value) {
     printf("%u", value);
 }
 
 template <>
-void print_value(const uint32_t& value) {
+void print_value(uint32_t value) {
     printf("%u", value);
 }
 
 template <>
-void print_value(const double& value) {
+void print_value(double value) {
     printf("%f", value);
 }
 
-// template <double>
-// void print_value(const double& value) {
-//     printf("%f", value);
-// }
-// 
-// template <char *>
-// void print_value(const char*& value) {
-//     printf("%f", value);
-// }
\ No newline at end of file
+template <>
+void print_value(char* value) {
+    printf("%s", value);
+}
\ No newline at end of file
diff --git a/nac3core/irrt/test/test_core.hpp b/nac3core/irrt/test/test_core.hpp
index ec2a5493..1d5b7d93 100644
--- a/nac3core/irrt/test/test_core.hpp
+++ b/nac3core/irrt/test/test_core.hpp
@@ -8,4 +8,8 @@ void test_int_exp() {
 
     assert_values_match(125, __nac3_int_exp_impl<int32_t>(5, 3));
     assert_values_match(3125, __nac3_int_exp_impl<int32_t>(5, 5));
+}
+
+void run_test_core() {
+    test_int_exp();
 }
\ No newline at end of file
diff --git a/nac3core/irrt/test/test_utils.hpp b/nac3core/irrt/test/test_utils.hpp
new file mode 100644
index 00000000..cad0da18
--- /dev/null
+++ b/nac3core/irrt/test/test_utils.hpp
@@ -0,0 +1,27 @@
+#pragma once
+
+#include "core.hpp"
+#include "../irrt/utils.hpp"
+
+void test_int_log_10() {
+    BEGIN_TEST();
+
+    assert_values_match((uint32_t) 0, int_log_floor(0, 10));
+    assert_values_match((uint32_t) 0, int_log_floor(9, 10));
+    assert_values_match((uint32_t) 1, int_log_floor(10, 10));
+    assert_values_match((uint32_t) 1, int_log_floor(11, 10));
+    assert_values_match((uint32_t) 1, int_log_floor(99, 10));
+    assert_values_match((uint32_t) 2, int_log_floor(100, 10));
+    assert_values_match((uint32_t) 2, int_log_floor(101, 10));
+}
+
+void test_cstr_utils() {
+    BEGIN_TEST();
+
+    assert_values_match((uint32_t) 42, (uint32_t) cstr_utils::length("THROWN FROM __nac3_error_dummy_raise!!!!!!"));
+}
+
+void run_test_utils() {
+    test_int_log_10();
+    test_cstr_utils();
+}
\ No newline at end of file
diff --git a/nac3core/src/codegen/irrt/classes.rs b/nac3core/src/codegen/irrt/classes.rs
index 195f04b7..dfa8c5d2 100644
--- a/nac3core/src/codegen/irrt/classes.rs
+++ b/nac3core/src/codegen/irrt/classes.rs
@@ -1,10 +1,32 @@
 use inkwell::types::{BasicTypeEnum, IntType};
 
-use crate::codegen::optics::{AddressLens, GepGetter, IntLens, StructureOptic};
+use crate::codegen::optics::{AddressLens, FieldBuilder, GepGetter, IntLens, StructureOptic};
 
-// use crate::codegen::structure::{
-//     FieldLensBuilder, IntLens, LensWithFieldInfo, PointerLens, StructFieldLens,
-// };
+#[derive(Debug, Clone)]
+pub struct StrLens<'ctx> {
+    pub size_type: IntType<'ctx>,
+}
+
+// TODO: nac3core has hardcoded a lot of "str"
+pub struct StrFields<'ctx> {
+    pub content: GepGetter<AddressLens<IntLens<'ctx>>>,
+    pub length: GepGetter<IntLens<'ctx>>,
+}
+
+impl<'ctx> StructureOptic<'ctx> for StrLens<'ctx> {
+    type Fields = StrFields<'ctx>;
+
+    fn struct_name(&self) -> &'static str {
+        "str"
+    }
+
+    fn build_fields(&self, builder: &mut FieldBuilder<'ctx>) -> Self::Fields {
+        StrFields {
+            content: builder.add_field("content", AddressLens(IntLens(builder.ctx.i8_type()))),
+            length: builder.add_field("length", IntLens(self.size_type)),
+        }
+    }
+}
 
 pub struct NpArrayFields<'ctx> {
     pub data: GepGetter<AddressLens<IntLens<'ctx>>>,
@@ -54,7 +76,7 @@ impl<'ctx> StructureOptic<'ctx> for IrrtStringLens {
     type Fields = IrrtStringFields<'ctx>;
 
     fn struct_name(&self) -> &'static str {
-        todo!()
+        "String"
     }
 
     fn build_fields(
@@ -71,15 +93,18 @@ impl<'ctx> StructureOptic<'ctx> for IrrtStringLens {
     }
 }
 
-pub struct ErrorContextFields {
-    pub message: GepGetter<IrrtStringLens>,
+pub struct ErrorContextFields<'ctx> {
+    pub message_template: GepGetter<AddressLens<IntLens<'ctx>>>,
+    pub param1: GepGetter<IntLens<'ctx>>,
+    pub param2: GepGetter<IntLens<'ctx>>,
+    pub param3: GepGetter<IntLens<'ctx>>,
 }
 
 #[derive(Debug, Clone, Copy)]
 pub struct ErrorContextLens;
 
 impl<'ctx> StructureOptic<'ctx> for ErrorContextLens {
-    type Fields = ErrorContextFields;
+    type Fields = ErrorContextFields<'ctx>;
 
     fn struct_name(&self) -> &'static str {
         "ErrorContext"
@@ -89,6 +114,12 @@ impl<'ctx> StructureOptic<'ctx> for ErrorContextLens {
         &self,
         builder: &mut crate::codegen::optics::FieldBuilder<'ctx>,
     ) -> Self::Fields {
-        ErrorContextFields { message: builder.add_field("message", IrrtStringLens) }
+        ErrorContextFields {
+            message_template: builder
+                .add_field("message_template", AddressLens(IntLens(builder.ctx.i8_type()))),
+            param1: builder.add_field("param1", IntLens(builder.ctx.i64_type())),
+            param2: builder.add_field("param2", IntLens(builder.ctx.i64_type())),
+            param3: builder.add_field("param3", IntLens(builder.ctx.i64_type())),
+        }
     }
 }
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index dfb91611..7276507e 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -23,6 +23,9 @@ use inkwell::{
 use itertools::Either;
 use nac3parser::ast::Expr;
 
+pub mod classes;
+pub mod new;
+
 #[must_use]
 pub fn load_irrt(ctx: &Context) -> Module {
     let bitcode_buf = MemoryBuffer::create_from_memory_range(
diff --git a/nac3core/src/codegen/irrt/new.rs b/nac3core/src/codegen/irrt/new.rs
new file mode 100644
index 00000000..5c992d4b
--- /dev/null
+++ b/nac3core/src/codegen/irrt/new.rs
@@ -0,0 +1,154 @@
+use inkwell::{
+    types::{BasicMetadataTypeEnum, BasicType, IntType},
+    values::{AnyValue, BasicMetadataValueEnum, IntValue},
+};
+
+use crate::{
+    codegen::{
+        optics::{Address, AddressLens, IntLens, Optic, OpticValue, Prism},
+        CodeGenContext, CodeGenerator,
+    },
+    util::SizeVariant,
+};
+
+use super::classes::{ErrorContextLens, StrLens};
+
+fn get_size_variant(ty: IntType) -> SizeVariant {
+    match ty.get_bit_width() {
+        32 => SizeVariant::Bits32,
+        64 => SizeVariant::Bits64,
+        _ => unreachable!("Unsupported int type bit width {}", ty.get_bit_width()),
+    }
+}
+
+fn get_sized_dependent_function_name(ty: IntType, fn_name: &str) -> String {
+    let mut fn_name = fn_name.to_owned();
+    match get_size_variant(ty) {
+        SizeVariant::Bits32 => {
+            // Do nothing, `fn_name` already has the correct name
+        }
+        SizeVariant::Bits64 => {
+            // Append "64", this is the naming convention
+            fn_name.push_str("64");
+        }
+    }
+    fn_name
+}
+
+// TODO: Variadic argument?
+pub struct FunctionBuilder<'ctx, 'a> {
+    ctx: &'a CodeGenContext<'ctx, 'a>,
+    fn_name: &'a str,
+    arguments: Vec<(BasicMetadataTypeEnum<'ctx>, BasicMetadataValueEnum<'ctx>)>,
+}
+
+impl<'ctx, 'a> FunctionBuilder<'ctx, 'a> {
+    pub fn begin(ctx: &'a CodeGenContext<'ctx, 'a>, fn_name: &'a str) -> Self {
+        FunctionBuilder { ctx, fn_name, arguments: Vec::new() }
+    }
+
+    // The name is for self-documentation
+    #[must_use]
+    pub fn arg<S: Optic<'ctx>>(mut self, _name: &'static str, optic: &S, arg: &S::Value) -> Self {
+        self.arguments
+            .push((optic.get_llvm_type(self.ctx.ctx).into(), arg.get_llvm_value().into()));
+        self
+    }
+
+    pub fn returning<S: Prism<'ctx>>(self, name: &'static str, return_prism: &S) -> S::Value {
+        let (param_tys, param_vals): (Vec<_>, Vec<_>) = self.arguments.into_iter().unzip();
+
+        let function = self.ctx.module.get_function(self.fn_name).unwrap_or_else(|| {
+            let return_type = return_prism.get_llvm_type(self.ctx.ctx);
+            let fn_type = return_type.fn_type(&param_tys, false);
+            self.ctx.module.add_function(self.fn_name, fn_type, None)
+        });
+
+        let ret = self.ctx.builder.build_call(function, &param_vals, name).unwrap();
+        return_prism.review(ret.as_any_value_enum())
+    }
+
+    // TODO: Code duplication, but otherwise returning<S: Optic<'ctx>> cannot resolve S if return_optic = None
+    pub fn returning_void(self) {
+        let (param_tys, param_vals): (Vec<_>, Vec<_>) = self.arguments.into_iter().unzip();
+
+        let function = self.ctx.module.get_function(self.fn_name).unwrap_or_else(|| {
+            let return_type = self.ctx.ctx.void_type();
+            let fn_type = return_type.fn_type(&param_tys, false);
+            self.ctx.module.add_function(self.fn_name, fn_type, None)
+        });
+
+        self.ctx.builder.build_call(function, &param_vals, "").unwrap();
+    }
+}
+
+pub fn call_nac3_error_context_initialize<'ctx>(
+    ctx: &CodeGenContext<'ctx, '_>,
+    errctx: &Address<'ctx, ErrorContextLens>,
+) {
+    FunctionBuilder::begin(ctx, "__nac3_error_context_initialize")
+        .arg("errctx", &AddressLens(ErrorContextLens), errctx)
+        .returning_void();
+}
+
+pub fn call_nac3_error_context_has_no_error<'ctx>(
+    ctx: &CodeGenContext<'ctx, '_>,
+    errctx: &Address<'ctx, ErrorContextLens>,
+) -> IntValue<'ctx> {
+    FunctionBuilder::begin(ctx, "__nac3_error_context_has_no_error")
+        .arg("errctx", &AddressLens(ErrorContextLens), errctx)
+        .returning("has_error", &IntLens(ctx.ctx.bool_type()))
+}
+
+pub fn call_nac3_error_context_get_error_str<'ctx>(
+    size_type: IntType<'ctx>,
+    ctx: &CodeGenContext<'ctx, '_>,
+    errctx: &Address<'ctx, ErrorContextLens>,
+    dst_str: &Address<'ctx, StrLens<'ctx>>,
+) -> IntValue<'ctx> {
+    FunctionBuilder::begin(
+        ctx,
+        &get_sized_dependent_function_name(size_type, "__nac3_error_context_get_error_str"),
+    )
+    .arg("errctx", &AddressLens(ErrorContextLens), errctx)
+    .arg("dst_str", &AddressLens(StrLens { size_type }), dst_str)
+    .returning("has_error", &IntLens(ctx.ctx.bool_type()))
+}
+
+pub fn call_nac3_dummy_raise<'ctx>(
+    ctx: &CodeGenContext<'ctx, '_>,
+    errctx: &Address<'ctx, ErrorContextLens>,
+) {
+    FunctionBuilder::begin(ctx, "__nac3_error_dummy_raise")
+        .arg("errctx", &AddressLens(ErrorContextLens), errctx)
+        .returning_void();
+}
+
+pub fn test_dummy_raise<G: CodeGenerator + ?Sized>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'_, '_>,
+) {
+    let size_type = generator.get_size_type(ctx.ctx);
+
+    let errctx_ptr = ErrorContextLens.alloca(ctx, "errctx");
+
+    call_nac3_error_context_initialize(ctx, &errctx_ptr);
+    call_nac3_dummy_raise(ctx, &errctx_ptr);
+
+    let has_error = call_nac3_error_context_has_no_error(ctx, &errctx_ptr);
+    let error_str_ptr = StrLens { size_type }.alloca(ctx, "error_str");
+    call_nac3_error_context_get_error_str(size_type, ctx, &errctx_ptr, &error_str_ptr);
+
+    let error_str = error_str_ptr.load(ctx, "error_str");
+    let param1 = errctx_ptr.view(ctx, |fields| &fields.param1).load(ctx, "param1");
+    let param2 = errctx_ptr.view(ctx, |fields| &fields.param2).load(ctx, "param2");
+    let param3 = errctx_ptr.view(ctx, |fields| &fields.param3).load(ctx, "param3");
+    ctx.make_assert_impl(
+        generator,
+        has_error,
+        "0:RuntimeError", // TODO: Make this dynamic (within IRRT), but this is probably not trivial
+        error_str.get_llvm_value(),
+        [Some(param1), Some(param2), Some(param3)],
+        ctx.current_loc,
+    );
+}
diff --git a/nac3core/src/codegen/irrt/test.rs b/nac3core/src/codegen/irrt/test.rs
index 9a91f41f..3174029d 100644
--- a/nac3core/src/codegen/irrt/test.rs
+++ b/nac3core/src/codegen/irrt/test.rs
@@ -11,7 +11,6 @@ mod tests {
 
         let irrt_test_out_path = Path::new(concat!(env!("OUT_DIR"), "/irrt_test.out"));
         let output = Command::new(irrt_test_out_path.to_str().unwrap()).output().unwrap();
-
         if !output.status.success() {
             eprintln!("irrt_test failed with status {}:", output.status);
             eprintln!("====== stdout ======");
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 11c4d4ef..dd7c4310 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -23,8 +23,10 @@ use inkwell::{
     values::{BasicValueEnum, FunctionValue, IntValue, PhiValue, PointerValue},
     AddressSpace, IntPredicate, OptimizationLevel,
 };
+use irrt::classes::StrLens;
 use itertools::Itertools;
 use nac3parser::ast::{Location, Stmt, StrRef};
+use optics::Optic;
 use parking_lot::{Condvar, Mutex};
 use std::collections::{HashMap, HashSet};
 use std::sync::{
@@ -647,6 +649,8 @@ pub fn gen_func_impl<
         ..primitives
     };
 
+    let llvm_str_ty =
+        StrLens { size_type: generator.get_size_type(context) }.get_llvm_type(context);
     let mut type_cache: HashMap<_, _> = [
         (primitives.int32, context.i32_type().into()),
         (primitives.int64, context.i64_type().into()),
@@ -654,21 +658,7 @@ pub fn gen_func_impl<
         (primitives.uint64, context.i64_type().into()),
         (primitives.float, context.f64_type().into()),
         (primitives.bool, context.i8_type().into()),
-        (primitives.str, {
-            let name = "str";
-            match module.get_struct_type(name) {
-                None => {
-                    let str_type = context.opaque_struct_type("str");
-                    let fields = [
-                        context.i8_type().ptr_type(AddressSpace::default()).into(),
-                        generator.get_size_type(context).into(),
-                    ];
-                    str_type.set_body(&fields, false);
-                    str_type.into()
-                }
-                Some(t) => t.as_basic_type_enum(),
-            }
-        }),
+        (primitives.str, llvm_str_ty),
         (primitives.range, RangeType::new(context).as_base_type().into()),
         (primitives.exception, {
             let name = "Exception";
@@ -678,7 +668,7 @@ pub fn gen_func_impl<
                 let exception = context.opaque_struct_type("Exception");
                 let int32 = context.i32_type().into();
                 let int64 = context.i64_type().into();
-                let str_ty = module.get_struct_type("str").unwrap().as_basic_type_enum();
+                let str_ty = llvm_str_ty;
                 let fields = [int32, str_ty, int32, int32, str_ty, str_ty, int64, int64, int64];
                 exception.set_body(&fields, false);
                 exception.ptr_type(AddressSpace::default()).as_basic_type_enum()
diff --git a/nac3core/src/codegen/optics.rs b/nac3core/src/codegen/optics.rs
index 0465ba9d..8a7b0439 100644
--- a/nac3core/src/codegen/optics.rs
+++ b/nac3core/src/codegen/optics.rs
@@ -173,7 +173,7 @@ impl<'ctx, AddresseeOptic: MemoryGetter<'ctx>> Address<'ctx, AddresseeOptic> {
 // To make [`Address`] convenient to use
 impl<'ctx, AddresseeOptic: MemorySetter<'ctx>> Address<'ctx, AddresseeOptic> {
     pub fn set(&self, ctx: &CodeGenContext<'ctx, '_>, value: &AddresseeOptic::Value) {
-        self.addressee_optic.set(ctx, self.address, value)
+        self.addressee_optic.set(ctx, self.address, value);
     }
 }
 
@@ -181,7 +181,7 @@ impl<'ctx, AddresseeOptic: MemorySetter<'ctx>> Address<'ctx, AddresseeOptic> {
 #[derive(Debug, Clone)]
 pub struct GepGetter<ElementOptic> {
     /// The LLVM GEP index
-    pub gep_index: u32, // TODO: I think I'm not supposed to *just* use i32 for GEP like that
+    pub gep_index: u64,
     /// Element (or field in the context of `struct`s) name. Used for cosmetics.
     pub name: &'static str,
     /// The lens to view the actual value after applying this [`FieldLens<T>`]
@@ -208,7 +208,7 @@ impl<'ctx, ElementOptic: Optic<'ctx>> MemoryGetter<'ctx> for GepGetter<ElementOp
             ctx.builder
                 .build_in_bounds_gep(
                     pointer,
-                    &[llvm_i32.const_zero(), llvm_i32.const_int(self.gep_index as u64, false)],
+                    &[llvm_i32.const_zero(), llvm_i32.const_int(self.gep_index, false)],
                     name,
                 )
                 .unwrap()
@@ -220,7 +220,7 @@ impl<'ctx, ElementOptic: Optic<'ctx>> MemoryGetter<'ctx> for GepGetter<ElementOp
 // Only used by [`FieldBuilder`]
 #[derive(Debug)]
 struct FieldInfo<'ctx> {
-    gep_index: u32,
+    gep_index: u64,
     name: &'ctx str,
     llvm_type: BasicTypeEnum<'ctx>,
 }
@@ -228,17 +228,18 @@ struct FieldInfo<'ctx> {
 #[derive(Debug)]
 pub struct FieldBuilder<'ctx> {
     pub ctx: &'ctx Context,
-    gep_index_counter: u32,
+    gep_index_counter: u64,
     struct_name: &'ctx str,
     fields: Vec<FieldInfo<'ctx>>,
 }
 
 impl<'ctx> FieldBuilder<'ctx> {
+    #[must_use]
     pub fn new(ctx: &'ctx Context, struct_name: &'ctx str) -> Self {
         FieldBuilder { ctx, gep_index_counter: 0, struct_name, fields: Vec::new() }
     }
 
-    fn next_gep_index(&mut self) -> u32 {
+    fn next_gep_index(&mut self) -> u64 {
         let index = self.gep_index_counter;
         self.gep_index_counter += 1;
         index
diff --git a/nac3core/src/toplevel/builtins.rs b/nac3core/src/toplevel/builtins.rs
index 0f6e8f24..1e8e5eef 100644
--- a/nac3core/src/toplevel/builtins.rs
+++ b/nac3core/src/toplevel/builtins.rs
@@ -1,5 +1,6 @@
 use std::iter::once;
 
+use crate::util::SizeVariant;
 use helper::{debug_assert_prim_is_allowed, make_exception_fields, PrimDefDetails};
 use indexmap::IndexMap;
 use inkwell::{
@@ -23,7 +24,6 @@ use crate::{
     symbol_resolver::SymbolValue,
     toplevel::{helper::PrimDef, numpy::make_ndarray_ty},
     typecheck::typedef::{into_var_map, iter_type_vars, TypeVar, VarMap},
-    util::SizeVariant,
 };
 
 use super::*;