diff --git a/bench_util/benches/utf8.rs b/bench_util/benches/utf8.rs
index 2bbf439b67..7a9066d1e0 100644
--- a/bench_util/benches/utf8.rs
+++ b/bench_util/benches/utf8.rs
@@ -6,12 +6,13 @@ use deno_bench_util::bencher::benchmark_group;
 use deno_bench_util::bencher::Bencher;
 use deno_bench_util::BenchOptions;
 use deno_core::Extension;
+use deno_core::ExtensionFileSource;
 
 fn setup() -> Vec<Extension> {
   vec![Extension::builder("bench_setup")
-    .js(vec![(
-      "setup.js",
-      r#"
+    .js(vec![ExtensionFileSource {
+      specifier: "setup.js".to_string(),
+      code: r#"
       const hello = "hello world\n";
       const hello1k = hello.repeat(1e3);
       const hello1m = hello.repeat(1e6);
@@ -19,7 +20,7 @@ fn setup() -> Vec<Extension> {
       const hello1kEncoded = Deno.core.encode(hello1k);
       const hello1mEncoded = Deno.core.encode(hello1m);
       "#,
-    )])
+    }])
     .build()]
 }
 
diff --git a/core/extensions.rs b/core/extensions.rs
index ba7bdb18ab..e08e8c5667 100644
--- a/core/extensions.rs
+++ b/core/extensions.rs
@@ -6,7 +6,10 @@ use std::rc::Rc;
 use std::task::Context;
 use v8::fast_api::FastFunction;
 
-pub type SourcePair = (String, &'static str);
+pub struct ExtensionFileSource {
+  pub specifier: String,
+  pub code: &'static str,
+}
 pub type OpFnRef = v8::FunctionCallback;
 pub type OpMiddlewareFn = dyn Fn(OpDecl) -> OpDecl;
 pub type OpStateFn = dyn Fn(&mut OpState) -> Result<(), Error>;
@@ -37,8 +40,8 @@ impl OpDecl {
 
 #[derive(Default)]
 pub struct Extension {
-  js_files: Option<Vec<SourcePair>>,
-  esm_files: Option<Vec<SourcePair>>,
+  js_files: Option<Vec<ExtensionFileSource>>,
+  esm_files: Option<Vec<ExtensionFileSource>>,
   ops: Option<Vec<OpDecl>>,
   opstate_fn: Option<Box<OpStateFn>>,
   middleware_fn: Option<Box<OpMiddlewareFn>>,
@@ -82,14 +85,14 @@ impl Extension {
 
   /// returns JS source code to be loaded into the isolate (either at snapshotting,
   /// or at startup).  as a vector of a tuple of the file name, and the source code.
-  pub fn get_js_sources(&self) -> &[SourcePair] {
+  pub fn get_js_sources(&self) -> &[ExtensionFileSource] {
     match &self.js_files {
       Some(files) => files,
       None => &[],
     }
   }
 
-  pub fn get_esm_sources(&self) -> &[SourcePair] {
+  pub fn get_esm_sources(&self) -> &[ExtensionFileSource] {
     match &self.esm_files {
       Some(files) => files,
       None => &[],
@@ -152,8 +155,8 @@ impl Extension {
 // Provides a convenient builder pattern to declare Extensions
 #[derive(Default)]
 pub struct ExtensionBuilder {
-  js: Vec<SourcePair>,
-  esm: Vec<SourcePair>,
+  js: Vec<ExtensionFileSource>,
+  esm: Vec<ExtensionFileSource>,
   ops: Vec<OpDecl>,
   state: Option<Box<OpStateFn>>,
   middleware: Option<Box<OpMiddlewareFn>>,
@@ -168,26 +171,27 @@ impl ExtensionBuilder {
     self
   }
 
-  pub fn js(
-    &mut self,
-    js_files: Vec<(&'static str, &'static str)>,
-  ) -> &mut Self {
-    let js_files = js_files.into_iter().map(|source_pair| {
-      let name = format!("internal:{}/{}", self.name, source_pair.0);
-      (name, source_pair.1)
-    });
+  pub fn js(&mut self, js_files: Vec<ExtensionFileSource>) -> &mut Self {
+    let js_files =
+      js_files.into_iter().map(|file_source| ExtensionFileSource {
+        specifier: format!("internal:{}/{}", self.name, file_source.specifier),
+        code: file_source.code,
+      });
     self.js.extend(js_files);
     self
   }
 
-  pub fn esm(
-    &mut self,
-    esm_files: Vec<(&'static str, &'static str)>,
-  ) -> &mut Self {
-    let esm_files = esm_files.into_iter().map(|source_pair| {
-      let name = format!("internal:{}/{}", self.name, source_pair.0);
-      (name, source_pair.1)
-    });
+  pub fn esm(&mut self, esm_files: Vec<ExtensionFileSource>) -> &mut Self {
+    let esm_files =
+      esm_files
+        .into_iter()
+        .map(|file_source| ExtensionFileSource {
+          specifier: format!(
+            "internal:{}/{}",
+            self.name, file_source.specifier
+          ),
+          code: file_source.code,
+        });
     self.esm.extend(esm_files);
     self
   }
@@ -254,10 +258,10 @@ impl ExtensionBuilder {
 macro_rules! include_js_files {
   ($($file:literal,)+) => {
     vec![
-      $((
-        $file,
-        include_str!($file),
-      ),)+
+      $($crate::ExtensionFileSource {
+        specifier: $file.to_string(),
+        code: include_str!($file),
+      },)+
     ]
   };
 }
diff --git a/core/lib.rs b/core/lib.rs
index 868d6b7493..86c432d43d 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -54,6 +54,7 @@ pub use crate::async_cell::RcLike;
 pub use crate::async_cell::RcRef;
 pub use crate::extensions::Extension;
 pub use crate::extensions::ExtensionBuilder;
+pub use crate::extensions::ExtensionFileSource;
 pub use crate::extensions::OpDecl;
 pub use crate::extensions::OpMiddlewareFn;
 pub use crate::flags::v8_set_flags;
diff --git a/core/runtime.rs b/core/runtime.rs
index 096d26ca3a..d4a9c697c8 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -815,27 +815,33 @@ impl JsRuntime {
     for ext in &extensions {
       {
         let js_files = ext.get_esm_sources();
-        for (filename, source) in js_files {
+        for file_source in js_files {
           futures::executor::block_on(async {
             let id = self
               .load_side_module(
-                &ModuleSpecifier::parse(filename)?,
-                Some(source.to_string()),
+                &ModuleSpecifier::parse(&file_source.specifier)?,
+                Some(file_source.code.to_string()),
               )
               .await?;
             let receiver = self.mod_evaluate(id);
             self.run_event_loop(false).await?;
             receiver.await?
           })
-          .with_context(|| format!("Couldn't execute '{filename}'"))?;
+          .with_context(|| {
+            format!("Couldn't execute '{}'", file_source.specifier)
+          })?;
         }
       }
 
       {
         let js_files = ext.get_js_sources();
-        for (filename, source) in js_files {
+        for file_source in js_files {
           // TODO(@AaronO): use JsRuntime::execute_static() here to move src off heap
-          realm.execute_script(self.v8_isolate(), filename, source)?;
+          realm.execute_script(
+            self.v8_isolate(),
+            &file_source.specifier,
+            file_source.code,
+          )?;
         }
       }
     }
diff --git a/ext/url/benches/url_ops.rs b/ext/url/benches/url_ops.rs
index fd8cac7ef0..001b5de926 100644
--- a/ext/url/benches/url_ops.rs
+++ b/ext/url/benches/url_ops.rs
@@ -6,18 +6,19 @@ use deno_bench_util::bencher::benchmark_group;
 use deno_bench_util::bencher::Bencher;
 
 use deno_core::Extension;
+use deno_core::ExtensionFileSource;
 
 fn setup() -> Vec<Extension> {
   vec![
     deno_webidl::init(),
     deno_url::init(),
     Extension::builder("bench_setup")
-      .esm(vec![(
-        "internal:setup",
-        r#"import { URL } from "internal:deno_url/00_url.js";
+      .esm(vec![ExtensionFileSource {
+        specifier: "internal:setup".to_string(),
+        code: r#"import { URL } from "internal:deno_url/00_url.js";
         globalThis.URL = URL;
         "#,
-      )])
+      }])
       .build(),
   ]
 }
diff --git a/ext/web/benches/encoding.rs b/ext/web/benches/encoding.rs
index a96da1bc63..bb297a1bfe 100644
--- a/ext/web/benches/encoding.rs
+++ b/ext/web/benches/encoding.rs
@@ -5,6 +5,7 @@ use deno_bench_util::bench_or_profile;
 use deno_bench_util::bencher::benchmark_group;
 use deno_bench_util::bencher::Bencher;
 use deno_core::Extension;
+use deno_core::ExtensionFileSource;
 use deno_web::BlobStore;
 
 struct Permissions;
@@ -29,14 +30,14 @@ fn setup() -> Vec<Extension> {
     deno_console::init(),
     deno_web::init::<Permissions>(BlobStore::default(), None),
     Extension::builder("bench_setup")
-      .esm(vec![(
-        "internal:setup",
-        r#"
+      .esm(vec![ExtensionFileSource {
+        specifier: "internal:setup".to_string(),
+        code: r#"
         import { TextDecoder } from "internal:deno_web/08_text_encoding.js";
         globalThis.TextDecoder = TextDecoder;
         globalThis.hello12k = Deno.core.encode("hello world\n".repeat(1e3));
         "#,
-      )])
+      }])
       .state(|state| {
         state.put(Permissions {});
         Ok(())
diff --git a/ext/web/benches/timers_ops.rs b/ext/web/benches/timers_ops.rs
index 943c73bbc0..f01b4c5323 100644
--- a/ext/web/benches/timers_ops.rs
+++ b/ext/web/benches/timers_ops.rs
@@ -5,6 +5,7 @@ use deno_bench_util::bench_or_profile;
 use deno_bench_util::bencher::benchmark_group;
 use deno_bench_util::bencher::Bencher;
 use deno_core::Extension;
+use deno_core::ExtensionFileSource;
 use deno_web::BlobStore;
 
 struct Permissions;
@@ -29,11 +30,14 @@ fn setup() -> Vec<Extension> {
     deno_web::init::<Permissions>(BlobStore::default(), None),
     Extension::builder("bench_setup")
     .esm(vec![
-      ("internal:setup", r#"
+      ExtensionFileSource {
+        specifier: "internal:setup".to_string(), 
+        code: r#"
       import { setTimeout, handleTimerMacrotask } from "internal:deno_web/02_timers.js";
       globalThis.setTimeout = setTimeout;
       Deno.core.setMacrotaskCallback(handleTimerMacrotask);
-      "#),
+      "#
+      },
     ])
     .state(|state| {
       state.put(Permissions{});
diff --git a/ext/webidl/benches/dict.rs b/ext/webidl/benches/dict.rs
index 1400a00ed5..00bef49350 100644
--- a/ext/webidl/benches/dict.rs
+++ b/ext/webidl/benches/dict.rs
@@ -6,12 +6,16 @@ use deno_bench_util::bencher::benchmark_group;
 use deno_bench_util::bencher::Bencher;
 
 use deno_core::Extension;
+use deno_core::ExtensionFileSource;
 
 fn setup() -> Vec<Extension> {
   vec![
     deno_webidl::init(),
     Extension::builder("deno_webidl_bench")
-      .esm(vec![("internal:setup", include_str!("dict.js"))])
+      .esm(vec![ExtensionFileSource {
+        specifier: "internal:setup".to_string(),
+        code: include_str!("dict.js"),
+      }])
       .build(),
   ]
 }