diff --git a/ast/src/module.rs b/ast/src/module.rs
index 769df5d162..59a02185be 100644
--- a/ast/src/module.rs
+++ b/ast/src/module.rs
@@ -1,10 +1,9 @@
+use bumpalo::Bump;
+use roc_load::{LoadedModule, Threading};
+use roc_target::TargetInfo;
 use std::path::Path;
 
-use bumpalo::Bump;
-use roc_load::LoadedModule;
-use roc_target::TargetInfo;
-
-pub fn load_module(src_file: &Path) -> LoadedModule {
+pub fn load_module(src_file: &Path, threading: Threading) -> LoadedModule {
     let subs_by_module = Default::default();
 
     let arena = Bump::new();
@@ -20,6 +19,7 @@ pub fn load_module(src_file: &Path) -> LoadedModule {
         subs_by_module,
         TargetInfo::default_x86_64(),
         roc_reporting::report::RenderTarget::ColorTerminal,
+        threading,
     );
 
     match loaded {
diff --git a/cli/src/build.rs b/cli/src/build.rs
index be2bd0736e..12e11bc409 100644
--- a/cli/src/build.rs
+++ b/cli/src/build.rs
@@ -4,7 +4,7 @@ use roc_build::{
     program::{self, Problems},
 };
 use roc_builtins::bitcode;
-use roc_load::LoadingProblem;
+use roc_load::{LoadingProblem, Threading};
 use roc_mono::ir::OptLevel;
 use roc_reporting::report::RenderTarget;
 use roc_target::TargetInfo;
@@ -40,6 +40,7 @@ pub fn build_file<'a>(
     surgically_link: bool,
     precompiled: bool,
     target_valgrind: bool,
+    threading: Threading,
 ) -> Result<BuiltFile, LoadingProblem<'a>> {
     let compilation_start = SystemTime::now();
     let target_info = TargetInfo::from(target);
@@ -55,6 +56,7 @@ pub fn build_file<'a>(
         target_info,
         // TODO: expose this from CLI?
         RenderTarget::ColorTerminal,
+        threading,
     )?;
 
     use target_lexicon::Architecture;
@@ -366,6 +368,7 @@ pub fn check_file(
         target_info,
         // TODO: expose this from CLI?
         RenderTarget::ColorTerminal,
+        Threading::Multi,
     )?;
 
     let buf = &mut String::with_capacity(1024);
diff --git a/cli/src/lib.rs b/cli/src/lib.rs
index b9d5e60f6a..d15e88e779 100644
--- a/cli/src/lib.rs
+++ b/cli/src/lib.rs
@@ -7,7 +7,7 @@ use clap::Command;
 use clap::{Arg, ArgMatches};
 use roc_build::link::LinkType;
 use roc_error_macros::user_error;
-use roc_load::LoadingProblem;
+use roc_load::{LoadingProblem, Threading};
 use roc_mono::ir::OptLevel;
 use std::env;
 use std::io;
@@ -386,6 +386,7 @@ pub fn build(matches: &ArgMatches, config: BuildConfig) -> io::Result<i32> {
         surgically_link,
         precompiled,
         target_valgrind,
+        Threading::Multi,
     );
 
     match res_binary_path {
diff --git a/compiler/load/build.rs b/compiler/load/build.rs
index ed424eb6eb..e0e5d643f8 100644
--- a/compiler/load/build.rs
+++ b/compiler/load/build.rs
@@ -1,6 +1,7 @@
 use std::path::PathBuf;
 
 use bumpalo::Bump;
+use roc_load_internal::file::Threading;
 use roc_module::symbol::ModuleId;
 
 const MODULES: &[(ModuleId, &str)] = &[
@@ -37,6 +38,7 @@ fn write_subs_for_module(module_id: ModuleId, filename: &str) {
         Default::default(),
         target_info,
         roc_reporting::report::RenderTarget::ColorTerminal,
+        Threading::Multi,
     );
 
     let module = res_module.unwrap();
diff --git a/compiler/load/src/lib.rs b/compiler/load/src/lib.rs
index 5d5c09daa4..bd5b215c4b 100644
--- a/compiler/load/src/lib.rs
+++ b/compiler/load/src/lib.rs
@@ -1,3 +1,5 @@
+pub use roc_load_internal::file::Threading;
+
 use bumpalo::Bump;
 use roc_collections::all::MutMap;
 use roc_constrain::module::ExposedByModule;
@@ -20,6 +22,7 @@ fn load<'a>(
     goal_phase: Phase,
     target_info: TargetInfo,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<LoadResult<'a>, LoadingProblem<'a>> {
     let cached_subs = read_cached_subs();
 
@@ -32,6 +35,7 @@ fn load<'a>(
         target_info,
         cached_subs,
         render,
+        threading,
     )
 }
 
@@ -67,6 +71,7 @@ pub fn load_and_monomorphize_from_str<'a>(
     exposed_types: ExposedByModule,
     target_info: TargetInfo,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<MonomorphizedModule<'a>, LoadingProblem<'a>> {
     use LoadResult::*;
 
@@ -80,6 +85,7 @@ pub fn load_and_monomorphize_from_str<'a>(
         Phase::MakeSpecializations,
         target_info,
         render,
+        threading,
     )? {
         Monomorphized(module) => Ok(module),
         TypeChecked(_) => unreachable!(""),
@@ -93,6 +99,7 @@ pub fn load_and_monomorphize<'a>(
     exposed_types: ExposedByModule,
     target_info: TargetInfo,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<MonomorphizedModule<'a>, LoadingProblem<'a>> {
     use LoadResult::*;
 
@@ -106,6 +113,7 @@ pub fn load_and_monomorphize<'a>(
         Phase::MakeSpecializations,
         target_info,
         render,
+        threading,
     )? {
         Monomorphized(module) => Ok(module),
         TypeChecked(_) => unreachable!(""),
@@ -119,6 +127,7 @@ pub fn load_and_typecheck<'a>(
     exposed_types: ExposedByModule,
     target_info: TargetInfo,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<LoadedModule, LoadingProblem<'a>> {
     use LoadResult::*;
 
@@ -132,6 +141,7 @@ pub fn load_and_typecheck<'a>(
         Phase::SolveTypes,
         target_info,
         render,
+        threading,
     )? {
         Monomorphized(_) => unreachable!(""),
         TypeChecked(module) => Ok(module),
diff --git a/compiler/load_internal/src/file.rs b/compiler/load_internal/src/file.rs
index fef510bdad..1905c85c52 100644
--- a/compiler/load_internal/src/file.rs
+++ b/compiler/load_internal/src/file.rs
@@ -956,6 +956,7 @@ pub fn load_and_typecheck_str<'a>(
     exposed_types: ExposedByModule,
     target_info: TargetInfo,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<LoadedModule, LoadingProblem<'a>> {
     use LoadResult::*;
 
@@ -974,6 +975,7 @@ pub fn load_and_typecheck_str<'a>(
         target_info,
         cached_subs,
         render,
+        threading,
     )? {
         Monomorphized(_) => unreachable!(""),
         TypeChecked(module) => Ok(module),
@@ -1091,6 +1093,12 @@ pub enum LoadResult<'a> {
     Monomorphized(MonomorphizedModule<'a>),
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum Threading {
+    Single,
+    Multi,
+}
+
 /// The loading process works like this, starting from the given filename (e.g. "main.roc"):
 ///
 /// 1. Open the file.
@@ -1144,10 +1152,11 @@ pub fn load<'a>(
     target_info: TargetInfo,
     cached_subs: MutMap<ModuleId, (Subs, Vec<(Symbol, Variable)>)>,
     render: RenderTarget,
+    threading: Threading,
 ) -> Result<LoadResult<'a>, LoadingProblem<'a>> {
     // When compiling to wasm, we cannot spawn extra threads
     // so we have a single-threaded implementation
-    if cfg!(target_family = "wasm") {
+    if threading == Threading::Single || cfg!(target_family = "wasm") {
         load_single_threaded(
             arena,
             load_start,
diff --git a/compiler/load_internal/tests/test_load.rs b/compiler/load_internal/tests/test_load.rs
index ae018333c1..de77f89913 100644
--- a/compiler/load_internal/tests/test_load.rs
+++ b/compiler/load_internal/tests/test_load.rs
@@ -19,6 +19,7 @@ mod test_load {
     use roc_can::def::Declaration::*;
     use roc_can::def::Def;
     use roc_constrain::module::ExposedByModule;
+    use roc_load_internal::file::Threading;
     use roc_load_internal::file::{LoadResult, LoadStart, LoadedModule, LoadingProblem, Phase};
     use roc_module::ident::ModuleName;
     use roc_module::symbol::{Interns, ModuleId};
@@ -53,6 +54,7 @@ mod test_load {
             target_info,
             Default::default(), // these tests will re-compile the builtins
             RenderTarget::Generic,
+            Threading::Single,
         )? {
             Monomorphized(_) => unreachable!(""),
             TypeChecked(module) => Ok(module),
diff --git a/compiler/test_gen/src/helpers/dev.rs b/compiler/test_gen/src/helpers/dev.rs
index 1210ce98e3..ab7ce02c2d 100644
--- a/compiler/test_gen/src/helpers/dev.rs
+++ b/compiler/test_gen/src/helpers/dev.rs
@@ -2,6 +2,7 @@ use libloading::Library;
 use roc_build::link::{link, LinkType};
 use roc_builtins::bitcode;
 use roc_collections::all::MutMap;
+use roc_load::Threading;
 use roc_region::all::LineInfo;
 use tempfile::tempdir;
 
@@ -55,6 +56,7 @@ pub fn helper(
         Default::default(),
         roc_target::TargetInfo::default_x86_64(),
         roc_reporting::report::RenderTarget::ColorTerminal,
+        Threading::Single,
     );
 
     let mut loaded = loaded.expect("failed to load module");
diff --git a/compiler/test_gen/src/helpers/llvm.rs b/compiler/test_gen/src/helpers/llvm.rs
index aeba51ad8c..d4c89f25e6 100644
--- a/compiler/test_gen/src/helpers/llvm.rs
+++ b/compiler/test_gen/src/helpers/llvm.rs
@@ -5,6 +5,7 @@ use roc_build::link::module_to_dylib;
 use roc_build::program::FunctionIterator;
 use roc_collections::all::MutSet;
 use roc_gen_llvm::llvm::externs::add_default_roc_externs;
+use roc_load::Threading;
 use roc_mono::ir::OptLevel;
 use roc_region::all::LineInfo;
 use roc_reporting::report::RenderTarget;
@@ -59,6 +60,7 @@ fn create_llvm_module<'a>(
         Default::default(),
         target_info,
         RenderTarget::ColorTerminal,
+        Threading::Multi,
     );
 
     let mut loaded = match loaded {
diff --git a/compiler/test_mono/src/tests.rs b/compiler/test_mono/src/tests.rs
index bcbaa4812f..1f64689c9d 100644
--- a/compiler/test_mono/src/tests.rs
+++ b/compiler/test_mono/src/tests.rs
@@ -16,9 +16,9 @@ const EXPANDED_STACK_SIZE: usize = 8 * 1024 * 1024;
 use test_mono_macros::*;
 
 use roc_collections::all::MutMap;
+use roc_load::Threading;
 use roc_module::symbol::Symbol;
 use roc_mono::ir::Proc;
-
 use roc_mono::ir::ProcLayout;
 
 const TARGET_INFO: roc_target::TargetInfo = roc_target::TargetInfo::default_x86_64();
@@ -99,6 +99,7 @@ fn compiles_to_ir(test_name: &str, src: &str) {
         Default::default(),
         TARGET_INFO,
         roc_reporting::report::RenderTarget::Generic,
+        Threading::Single,
     );
 
     let mut loaded = match loaded {
diff --git a/docs/src/lib.rs b/docs/src/lib.rs
index 4a22876060..bff952e22a 100644
--- a/docs/src/lib.rs
+++ b/docs/src/lib.rs
@@ -10,7 +10,7 @@ use roc_highlight::highlight_parser::{highlight_defs, highlight_expr};
 use roc_load::docs::DocEntry::DocDef;
 use roc_load::docs::{DocEntry, TypeAnnotation};
 use roc_load::docs::{ModuleDocumentation, RecordField};
-use roc_load::{LoadedModule, LoadingProblem};
+use roc_load::{LoadedModule, LoadingProblem, Threading};
 use roc_module::symbol::{IdentIdsByModule, Interns, ModuleId};
 use roc_parse::ident::{parse_ident, Ident};
 use roc_parse::state::State;
@@ -435,6 +435,7 @@ pub fn load_modules_for_files(filenames: Vec<PathBuf>) -> Vec<LoadedModule> {
             Default::default(),
             roc_target::TargetInfo::default_x86_64(), // This is just type-checking for docs, so "target" doesn't matter
             roc_reporting::report::RenderTarget::ColorTerminal,
+            Threading::Multi,
         ) {
             Ok(loaded) => modules.push(loaded),
             Err(LoadingProblem::FormattedReport(report)) => {
diff --git a/editor/src/editor/main.rs b/editor/src/editor/main.rs
index cac5843445..8c6219d984 100644
--- a/editor/src/editor/main.rs
+++ b/editor/src/editor/main.rs
@@ -26,6 +26,7 @@ use pipelines::RectResources;
 use roc_ast::lang::env::Env;
 use roc_ast::mem_pool::pool::Pool;
 use roc_ast::module::load_module;
+use roc_load::Threading;
 use roc_module::symbol::IdentIds;
 use roc_types::subs::VarStore;
 use std::collections::HashSet;
@@ -128,7 +129,7 @@ fn run_event_loop(project_dir_path_opt: Option<&Path>) -> Result<(), Box<dyn Err
 
     let file_path = Path::new(&file_path_str);
 
-    let loaded_module = load_module(file_path);
+    let loaded_module = load_module(file_path, Threading::Multi);
 
     let mut var_store = VarStore::default();
     let dep_idents = IdentIds::exposed_builtins(8);
diff --git a/editor/src/editor/mvc/ed_model.rs b/editor/src/editor/mvc/ed_model.rs
index bc4f6f540e..4cdc906f55 100644
--- a/editor/src/editor/mvc/ed_model.rs
+++ b/editor/src/editor/mvc/ed_model.rs
@@ -234,7 +234,7 @@ pub mod test_ed_model {
     use roc_ast::lang::env::Env;
     use roc_ast::mem_pool::pool::Pool;
     use roc_ast::module::load_module;
-    use roc_load::LoadedModule;
+    use roc_load::{LoadedModule, Threading};
     use roc_module::symbol::IdentIds;
     use roc_module::symbol::ModuleIds;
     use roc_types::subs::VarStore;
@@ -330,7 +330,7 @@ pub mod test_ed_model {
         writeln!(file, "{}", clean_code_str)
             .unwrap_or_else(|_| panic!("Failed to write {:?} to file: {:?}", clean_code_str, file));
 
-        let loaded_module = load_module(&temp_file_full_path);
+        let loaded_module = load_module(&temp_file_full_path, Threading::Multi);
 
         let mut ed_model = init_dummy_model(
             clean_code_str,
diff --git a/repl_eval/src/gen.rs b/repl_eval/src/gen.rs
index 3c50ffa14d..a20b20f6f9 100644
--- a/repl_eval/src/gen.rs
+++ b/repl_eval/src/gen.rs
@@ -1,4 +1,5 @@
 use bumpalo::Bump;
+use roc_load::Threading;
 use roc_reporting::report::Palette;
 use std::path::{Path, PathBuf};
 
@@ -61,6 +62,7 @@ pub fn compile_to_mono<'a>(
         exposed_types,
         target_info,
         roc_reporting::report::RenderTarget::ColorTerminal,
+        Threading::Single,
     );
 
     let mut loaded = match loaded {
diff --git a/reporting/tests/test_reporting.rs b/reporting/tests/test_reporting.rs
index a88ad14ecb..fa950fdaac 100644
--- a/reporting/tests/test_reporting.rs
+++ b/reporting/tests/test_reporting.rs
@@ -12,7 +12,7 @@ mod test_reporting {
     use bumpalo::Bump;
     use indoc::indoc;
     use roc_can::abilities::AbilitiesStore;
-    use roc_load::{self, LoadedModule, LoadingProblem};
+    use roc_load::{self, LoadedModule, LoadingProblem, Threading};
     use roc_module::symbol::{Interns, ModuleId};
     use roc_region::all::LineInfo;
     use roc_reporting::report::{
@@ -92,6 +92,7 @@ mod test_reporting {
                 exposed_types,
                 roc_target::TargetInfo::default_x86_64(),
                 RenderTarget::Generic,
+                Threading::Single,
             );
             drop(file);