diff --git a/nac3artiq/src/lib.rs b/nac3artiq/src/lib.rs
index 32fe0218..0badf1ce 100644
--- a/nac3artiq/src/lib.rs
+++ b/nac3artiq/src/lib.rs
@@ -33,6 +33,7 @@ use inkwell::{
     OptimizationLevel,
 };
 use itertools::Itertools;
+use nac3core::codegen::irrt::setup_irrt_exceptions;
 use nac3core::codegen::{gen_func_impl, CodeGenLLVMOptions, CodeGenTargetMachineOptions};
 use nac3core::toplevel::builtins::get_exn_constructor;
 use nac3core::typecheck::typedef::{TypeEnum, Unifier, VarMap};
@@ -498,6 +499,11 @@ impl Nac3 {
             .register_top_level(synthesized.pop().unwrap(), Some(resolver.clone()), "", false)
             .unwrap();
 
+        // Process IRRT
+        let context = inkwell::context::Context::create();
+        let irrt = load_irrt(&context);
+        setup_irrt_exceptions(&context, &irrt, resolver.as_ref());
+
         let fun_signature =
             FunSignature { args: vec![], ret: self.primitive.none, vars: VarMap::new() };
         let mut store = ConcreteTypeStore::new();
@@ -668,7 +674,7 @@ impl Nac3 {
             membuffer.lock().push(buffer);
         });
 
-        let context = inkwell::context::Context::create();
+        // Link all modules into `main`.
         let buffers = membuffers.lock();
         let main = context
             .create_module_from_ir(MemoryBuffer::create_from_memory_range(&buffers[0], "main"))
@@ -697,8 +703,7 @@ impl Nac3 {
             )
             .unwrap();
 
-        main.link_in_module(load_irrt(&context))
-            .map_err(|err| CompileError::new_err(err.to_string()))?;
+        main.link_in_module(irrt).map_err(|err| CompileError::new_err(err.to_string()))?;
 
         let mut function_iter = main.get_first_function();
         while let Some(func) = function_iter {
diff --git a/nac3core/irrt/irrt/cslice.hpp b/nac3core/irrt/irrt/cslice.hpp
new file mode 100644
index 00000000..f46b464a
--- /dev/null
+++ b/nac3core/irrt/irrt/cslice.hpp
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <irrt/int_defs.hpp>
+
+template <typename SizeT>
+struct CSlice {
+    uint8_t* base;
+    SizeT len;
+};
\ No newline at end of file
diff --git a/nac3core/irrt/irrt/exception.hpp b/nac3core/irrt/irrt/exception.hpp
new file mode 100644
index 00000000..9d68f8cd
--- /dev/null
+++ b/nac3core/irrt/irrt/exception.hpp
@@ -0,0 +1,123 @@
+#pragma once
+
+#include <irrt/cslice.hpp>
+#include <irrt/int_defs.hpp>
+#include <irrt/util.hpp>
+
+/**
+ * @brief The int type of ARTIQ exception IDs.
+ *
+ * It is always `int32_t`
+ */
+typedef int32_t ExceptionId;
+
+/*
+ * A set of exceptions IRRT can use.
+ * Must be synchronized with `setup_irrt_exceptions` in `nac3core/src/codegen/irrt/mod.rs`.
+ * All exception IDs are initialized by `setup_irrt_exceptions`.
+ */
+#ifdef IRRT_TESTING
+// If we are doing IRRT tests (i.e., running `cargo test -F test`), define them with a fake set of IDs.
+ExceptionId EXN_INDEX_ERROR = 0;
+ExceptionId EXN_VALUE_ERROR = 1;
+ExceptionId EXN_ASSERTION_ERROR = 2;
+ExceptionId EXN_RUNTIME_ERROR = 3;
+ExceptionId EXN_TYPE_ERROR = 4;
+#else
+extern "C" {
+ExceptionId EXN_INDEX_ERROR;
+ExceptionId EXN_VALUE_ERROR;
+ExceptionId EXN_ASSERTION_ERROR;
+ExceptionId EXN_RUNTIME_ERROR;
+ExceptionId EXN_TYPE_ERROR;
+}
+#endif
+
+namespace {
+/**
+ * @brief NAC3's Exception struct
+ */
+template <typename SizeT>
+struct Exception {
+    ExceptionId id;
+    CSlice<SizeT> filename;
+    int32_t line;
+    int32_t column;
+    CSlice<SizeT> function;
+    CSlice<SizeT> msg;
+    int64_t params[3];
+};
+}  // namespace
+
+// Declare/Define `__nac3_raise`
+#ifdef IRRT_TESTING
+#include <cstdio>
+void __nac3_raise(void* err) {
+    // TODO: Print the error content?
+    printf("__nac3_raise called. Exiting...\n");
+    exit(1);
+}
+#else
+/**
+ * @brief Extern function to `__nac3_raise`
+ *
+ * The parameter `err` could be `Exception<int32_t>` or `Exception<int64_t>`. The caller
+ * must make sure to pass `Exception`s with the correct `SizeT` depending on the `size_t` of the runtime.
+ */
+extern "C" void __nac3_raise(void* err);
+#endif
+
+namespace {
+const int64_t NO_PARAM = 0;
+
+// Helper function to raise an exception with `__nac3_raise`
+// Do not use this function directly. See `raise_exception`.
+template <typename SizeT>
+void _raise_exception_helper(ExceptionId id, const char* filename, int32_t line,
+                             const char* function, const char* msg,
+                             int64_t param0, int64_t param1, int64_t param2) {
+    Exception<SizeT> e = {
+        .id = id,
+        .filename = {.base = (uint8_t*)filename,
+                     .len = (int32_t)cstr_utils::length(filename)},
+        .line = line,
+        .column = 0,
+        .function = {.base = (uint8_t*)function,
+                     .len = (int32_t)cstr_utils::length(function)},
+        .msg = {.base = (uint8_t*)msg, .len = (int32_t)cstr_utils::length(msg)},
+    };
+    e.params[0] = param0;
+    e.params[1] = param1;
+    e.params[2] = param2;
+    __nac3_raise((void*)&e);
+    __builtin_unreachable();
+}
+
+/**
+ * @brief Raise an exception with location details (location in the IRRT source files).
+ * @param SizeT The runtime `size_t` type.
+ * @param id The ID of the exception to raise.
+ * @param msg A global constant C-string of the error message.
+ *
+ * `param0` and `param2` are optional format arguments of `msg`. They should be set to
+ * `NO_PARAM` to indicate they are unused.
+ */
+#define raise_exception(SizeT, id, msg, param0, param1, param2)               \
+    _raise_exception_helper<SizeT>(id, __FILE__, __LINE__, __FUNCTION__, msg, \
+                                   param0, param1, param2)
+
+/**
+ * @brief Throw a dummy error for testing.
+ */
+template <typename SizeT>
+void throw_dummy_error() {
+    raise_exception(SizeT, EXN_RUNTIME_ERROR, "dummy error", NO_PARAM, NO_PARAM,
+                    NO_PARAM);
+}
+}  // namespace
+
+extern "C" {
+void __nac3_throw_dummy_error() { throw_dummy_error<int32_t>(); }
+
+void __nac3_throw_dummy_error64() { throw_dummy_error<int64_t>(); }
+}
\ No newline at end of file
diff --git a/nac3core/irrt/irrt_everything.hpp b/nac3core/irrt/irrt_everything.hpp
index 78335c19..636a011c 100644
--- a/nac3core/irrt/irrt_everything.hpp
+++ b/nac3core/irrt/irrt_everything.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
 #include <irrt/core.hpp>
+#include <irrt/exception.hpp>
 #include <irrt/int_defs.hpp>
 #include <irrt/util.hpp>
\ No newline at end of file
diff --git a/nac3core/irrt/irrt_test.cpp b/nac3core/irrt/irrt_test.cpp
index 355dc01f..7ffa2e66 100644
--- a/nac3core/irrt/irrt_test.cpp
+++ b/nac3core/irrt/irrt_test.cpp
@@ -1,9 +1,15 @@
 // This file will be compiled like a real C++ program,
 // and we do have the luxury to use the standard libraries.
 // That is if the nix flakes do not have issues... especially on msys2...
+
 #include <cstdint>
 #include <cstdio>
 #include <cstdlib>
+
+// Special macro to inform `#include <irrt/*>` that we
+// are testing.
+#define IRRT_TESTING
+
 #include <test/test_core.hpp>
 
 int main() {
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 2a4c8b83..9150afe8 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -1,6 +1,8 @@
+use crate::symbol_resolver::SymbolResolver;
 use crate::typecheck::typedef::Type;
 
 mod test;
+pub mod util;
 
 use super::model::*;
 use super::{
@@ -12,6 +14,7 @@ use super::{
 };
 use crate::codegen::classes::TypedArrayLikeAccessor;
 use crate::codegen::stmt::gen_for_callback_incrementing;
+use inkwell::values::BasicValue;
 use inkwell::{
     attributes::{Attribute, AttributeLoc},
     context::Context,
@@ -23,6 +26,8 @@ use inkwell::{
 };
 use itertools::Either;
 use nac3parser::ast::Expr;
+use util::function::CallFunction;
+use util::get_sizet_dependent_function_name;
 
 #[must_use]
 pub fn load_irrt(ctx: &Context) -> Module {
@@ -946,3 +951,39 @@ pub fn call_ndarray_calc_broadcast_index<
         Box::new(|_, v| v.into()),
     )
 }
+
+pub fn call_nac3_throw_dummy_error<'ctx>(tyctx: TypeContext<'ctx>, ctx: &CodeGenContext<'ctx, '_>) {
+    CallFunction::begin(
+        tyctx,
+        ctx,
+        &get_sizet_dependent_function_name(tyctx, "__nac3_throw_dummy_error"),
+    )
+    .returning_void();
+}
+
+/// Initialize all global `EXN_*` exception IDs in IRRT with the [`SymbolResolver`].
+pub fn setup_irrt_exceptions<'ctx>(
+    ctx: &'ctx Context,
+    module: &Module<'ctx>,
+    symbol_resolver: &dyn SymbolResolver,
+) {
+    let exn_id_type = ctx.i32_type();
+
+    let errors = &[
+        ("EXN_INDEX_ERROR", "0:IndexError"),
+        ("EXN_VALUE_ERROR", "0:ValueError"),
+        ("EXN_ASSERTION_ERROR", "0:AssertionError"),
+        ("EXN_RUNTIME_ERROR", "0:RuntimeError"),
+        ("EXN_TYPE_ERROR", "0:TypeError"),
+    ];
+
+    for (irrt_name, symbol_name) in errors {
+        let exn_id = symbol_resolver.get_string_id(symbol_name);
+        let exn_id = exn_id_type.const_int(exn_id as u64, false).as_basic_value_enum();
+
+        let global = module.get_global(irrt_name).unwrap_or_else(|| {
+            panic!("Exception symbol name '{irrt_name}' should exist in the IRRT LLVM module")
+        });
+        global.set_initializer(&exn_id);
+    }
+}
diff --git a/nac3core/src/codegen/irrt/util.rs b/nac3core/src/codegen/irrt/util.rs
new file mode 100644
index 00000000..1f2776f8
--- /dev/null
+++ b/nac3core/src/codegen/irrt/util.rs
@@ -0,0 +1,105 @@
+use crate::codegen::model::*;
+
+// When [`TypeContext::size_type`] is 32-bits, the function name is "{fn_name}".
+// When [`TypeContext::size_type`] is 64-bits, the function name is "{fn_name}64".
+#[must_use]
+pub fn get_sizet_dependent_function_name(tyctx: TypeContext<'_>, name: &str) -> String {
+    let mut name = name.to_owned();
+    match tyctx.size_type.get_bit_width() {
+        32 => {}
+        64 => name.push_str("64"),
+        bit_width => {
+            panic!("Unsupported int type bit width {bit_width}, must be either 32-bits or 64-bits")
+        }
+    }
+    name
+}
+
+pub mod function {
+    use crate::codegen::{model::*, CodeGenContext};
+    use inkwell::{
+        types::{BasicMetadataTypeEnum, BasicType, FunctionType},
+        values::{AnyValue, BasicMetadataValueEnum, BasicValue, BasicValueEnum, CallSiteValue},
+    };
+    use itertools::Itertools;
+
+    #[derive(Debug, Clone, Copy)]
+    struct Arg<'ctx> {
+        ty: BasicMetadataTypeEnum<'ctx>,
+        val: BasicMetadataValueEnum<'ctx>,
+    }
+
+    /// Helper structure to reduce IRRT Inkwell function call boilerplate
+    pub struct CallFunction<'ctx, 'a, 'b, 'c> {
+        tyctx: TypeContext<'ctx>,
+        ctx: &'b CodeGenContext<'ctx, 'a>,
+        /// Function name
+        name: &'c str,
+        /// Call arguments
+        args: Vec<Arg<'ctx>>,
+    }
+
+    impl<'ctx, 'a, 'b, 'c> CallFunction<'ctx, 'a, 'b, 'c> {
+        pub fn begin(
+            tyctx: TypeContext<'ctx>,
+            ctx: &'b CodeGenContext<'ctx, 'a>,
+            name: &'c str,
+        ) -> Self {
+            CallFunction { tyctx, ctx, name, args: Vec::new() }
+        }
+
+        /// Push a call argument to the function call.
+        ///
+        /// The `_name` parameter is there for self-documentation purposes.
+        #[allow(clippy::needless_pass_by_value)]
+        #[must_use]
+        pub fn arg<M: Model<'ctx>>(mut self, _name: &str, arg: Instance<'ctx, M>) -> Self {
+            let arg = Arg {
+                ty: arg.model.get_type(self.tyctx, self.ctx.ctx).as_basic_type_enum().into(),
+                val: arg.value.as_basic_value_enum().into(),
+            };
+            self.args.push(arg);
+            self
+        }
+
+        /// Call the function and expect the function to return a value of type of `return_model`.
+        #[must_use]
+        pub fn returning<M: Model<'ctx>>(self, name: &str, return_model: M) -> Instance<'ctx, M> {
+            let ret_ty = return_model.get_type(self.tyctx, self.ctx.ctx);
+
+            let ret = self.get_function(|tys| ret_ty.fn_type(tys, false), name);
+            let ret = BasicValueEnum::try_from(ret.as_any_value_enum()).unwrap(); // Must work
+            let ret = return_model.check_value(self.tyctx, self.ctx.ctx, ret).unwrap(); // Must work
+            ret
+        }
+
+        /// Like [`CallFunction::returning_`] but `return_model` is automatically inferred.
+        #[must_use]
+        pub fn returning_auto<M: Model<'ctx> + Default>(self, name: &str) -> Instance<'ctx, M> {
+            self.returning(name, M::default())
+        }
+
+        /// Call the function and expect the function to return a void-type.
+        pub fn returning_void(self) {
+            let ret_ty = self.ctx.ctx.void_type();
+
+            let _ = self.get_function(|tys| ret_ty.fn_type(tys, false), "");
+        }
+
+        fn get_function<F>(&self, make_fn_type: F, return_value_name: &str) -> CallSiteValue<'ctx>
+        where
+            F: FnOnce(&[BasicMetadataTypeEnum<'ctx>]) -> FunctionType<'ctx>,
+        {
+            // Get the LLVM function, declare the function if it doesn't exist - it will be defined by other
+            // components of NAC3.
+            let func = self.ctx.module.get_function(self.name).unwrap_or_else(|| {
+                let tys = self.args.iter().map(|arg| arg.ty).collect_vec();
+                let fn_type = make_fn_type(&tys);
+                self.ctx.module.add_function(self.name, fn_type, None)
+            });
+
+            let vals = self.args.iter().map(|arg| arg.val).collect_vec();
+            self.ctx.builder.build_call(func, &vals, return_value_name).unwrap()
+        }
+    }
+}
diff --git a/nac3standalone/src/main.rs b/nac3standalone/src/main.rs
index 228b75c4..7d99fad5 100644
--- a/nac3standalone/src/main.rs
+++ b/nac3standalone/src/main.rs
@@ -14,6 +14,7 @@ use inkwell::{
     memory_buffer::MemoryBuffer, passes::PassBuilderOptions, support::is_multithreaded, targets::*,
     OptimizationLevel,
 };
+use nac3core::codegen::irrt::setup_irrt_exceptions;
 use nac3core::{
     codegen::{
         concrete_type::ConcreteTypeStore, irrt::load_irrt, CodeGenLLVMOptions,
@@ -314,6 +315,16 @@ fn main() {
     let resolver =
         Arc::new(Resolver(internal_resolver.clone())) as Arc<dyn SymbolResolver + Send + Sync>;
 
+    let context = inkwell::context::Context::create();
+
+    // Process IRRT
+    let irrt = load_irrt(&context);
+    setup_irrt_exceptions(&context, &irrt, resolver.as_ref());
+    if emit_llvm {
+        irrt.write_bitcode_to_path(Path::new("irrt.bc"));
+    }
+
+    // Process the Python script
     let parser_result = parser::parse_program(&program, file_name.into()).unwrap();
 
     for stmt in parser_result {
@@ -418,8 +429,8 @@ fn main() {
     registry.add_task(task);
     registry.wait_tasks_complete(handles);
 
+    // Link all modules together into `main`
     let buffers = membuffers.lock();
-    let context = inkwell::context::Context::create();
     let main = context
         .create_module_from_ir(MemoryBuffer::create_from_memory_range(&buffers[0], "main"))
         .unwrap();
@@ -439,12 +450,9 @@ fn main() {
         main.link_in_module(other).unwrap();
     }
 
-    let irrt = load_irrt(&context);
-    if emit_llvm {
-        irrt.write_bitcode_to_path(Path::new("irrt.bc"));
-    }
     main.link_in_module(irrt).unwrap();
 
+    // Private all functions except "run"
     let mut function_iter = main.get_first_function();
     while let Some(func) = function_iter {
         if func.count_basic_blocks() > 0 && func.get_name().to_str().unwrap() != "run" {
@@ -453,6 +461,7 @@ fn main() {
         function_iter = func.get_next_function();
     }
 
+    // Optimize `main`
     let target_machine = llvm_options
         .target
         .create_target_machine(llvm_options.opt_level)
@@ -466,6 +475,7 @@ fn main() {
         panic!("Failed to run optimization for module `main`: {}", err.to_string());
     }
 
+    // Write output
     target_machine
         .write_to_file(&main, FileType::Object, Path::new("module.o"))
         .expect("couldn't write module to file");