diff --git a/api/src/analysis.rs b/api/src/analysis.rs
index fd5bfa9c..a66de38a 100644
--- a/api/src/analysis.rs
+++ b/api/src/analysis.rs
@@ -186,6 +186,7 @@ async fn analyze_package_inner(
       .analyzer
       .get_parsed_source(module.specifier())
     {
+      check_for_banned_extensions(&parsed_source)?;
       check_for_banned_syntax(&parsed_source)?;
       check_for_banned_triple_slash_directives(&parsed_source)?;
     }
@@ -802,6 +803,21 @@ fn collect_dependencies(
   Ok(dependencies)
 }
 
+fn check_for_banned_extensions(
+  parsed_source: &ParsedSource,
+) -> Result<(), PublishError> {
+  match parsed_source.media_type() {
+    deno_ast::MediaType::Cjs | deno_ast::MediaType::Cts => {
+      Err(PublishError::CommonJs {
+        specifier: parsed_source.specifier().to_string(),
+        line: 0,
+        column: 0,
+      })
+    }
+    _ => Ok(()),
+  }
+}
+
 fn check_for_banned_syntax(
   parsed_source: &ParsedSource,
 ) -> Result<(), PublishError> {
@@ -957,8 +973,15 @@ fn check_for_banned_triple_slash_directives(
 #[cfg(test)]
 mod tests {
   fn parse(source: &str) -> deno_ast::ParsedSource {
-    let specifier = deno_ast::ModuleSpecifier::parse("file:///mod.ts").unwrap();
     let media_type = deno_ast::MediaType::TypeScript;
+    parse_with_media_type(source, media_type)
+  }
+
+  fn parse_with_media_type(
+    source: &str,
+    media_type: deno_ast::MediaType,
+  ) -> deno_ast::ParsedSource {
+    let specifier = deno_ast::ModuleSpecifier::parse("file:///mod.ts").unwrap();
     deno_ast::parse_module(deno_ast::ParseParams {
       specifier,
       text: source.into(),
@@ -970,6 +993,27 @@ mod tests {
     .unwrap()
   }
 
+  #[test]
+  fn banned_extensions() {
+    let x =
+      parse_with_media_type("let x = 1;", deno_ast::MediaType::TypeScript);
+    assert!(super::check_for_banned_extensions(&x).is_ok());
+
+    let x = parse_with_media_type("let x = 1;", deno_ast::MediaType::Cjs);
+    let err = super::check_for_banned_extensions(&x).unwrap_err();
+    assert!(
+      matches!(err, super::PublishError::CommonJs { .. }),
+      "{err:?}",
+    );
+
+    let x = parse_with_media_type("let x = 1;", deno_ast::MediaType::Cts);
+    let err = super::check_for_banned_extensions(&x).unwrap_err();
+    assert!(
+      matches!(err, super::PublishError::CommonJs { .. }),
+      "{err:?}",
+    );
+  }
+
   #[test]
   fn banned_triple_slash_directives() {
     let x = parse("let x = 1;");
diff --git a/api/src/gcp.rs b/api/src/gcp.rs
index 7dffbbd9..37f847f6 100644
--- a/api/src/gcp.rs
+++ b/api/src/gcp.rs
@@ -573,12 +573,18 @@ impl FakeGcsTester {
 
     assert!(self.proc.is_none());
 
-    #[cfg(target_os = "macos")]
+    #[cfg(all(target_os = "macos", target_arch = "aarch64"))]
     let p = concat!(
       env!("CARGO_MANIFEST_DIR"),
       "/../tools/bin/darwin-arm64/fake-gcs-server"
     );
 
+    #[cfg(all(target_os = "macos", target_arch = "x86_64"))]
+    let p = concat!(
+      env!("CARGO_MANIFEST_DIR"),
+      "/../tools/bin/darwin-amd64/fake-gcs-server"
+    );
+
     #[cfg(target_os = "linux")]
     let p = concat!(
       env!("CARGO_MANIFEST_DIR"),
diff --git a/api/src/publish.rs b/api/src/publish.rs
index e2df5d91..85118fd9 100644
--- a/api/src/publish.rs
+++ b/api/src/publish.rs
@@ -1309,6 +1309,16 @@ pub mod tests {
     assert_eq!(task.status, PublishingTaskStatus::Success, "{task:#?}");
   }
 
+  #[tokio::test]
+  async fn cjs_import() {
+    let t = TestSetup::new().await;
+    let bytes = create_mock_tarball("cjs_import");
+    let task = process_tarball_setup(&t, bytes).await;
+    assert_eq!(task.status, PublishingTaskStatus::Failure, "{task:#?}");
+    let error = task.error.unwrap();
+    assert_eq!(error.code, "commonJs");
+  }
+
   #[tokio::test]
   async fn npm_tarball() {
     let t = TestSetup::new().await;
diff --git a/api/testdata/tarballs/cjs_import/jsr.json b/api/testdata/tarballs/cjs_import/jsr.json
new file mode 100644
index 00000000..35b9ed05
--- /dev/null
+++ b/api/testdata/tarballs/cjs_import/jsr.json
@@ -0,0 +1,5 @@
+{
+  "name": "@scope/foo",
+  "version": "1.2.3",
+  "exports": "./mod.ts"
+}
\ No newline at end of file
diff --git a/api/testdata/tarballs/cjs_import/mod.ts b/api/testdata/tarballs/cjs_import/mod.ts
new file mode 100644
index 00000000..5455679a
--- /dev/null
+++ b/api/testdata/tarballs/cjs_import/mod.ts
@@ -0,0 +1,3 @@
+import { test } from "./other.cjs"; // bad
+
+export const hello = `Hello, ${test}!`;
diff --git a/api/testdata/tarballs/cjs_import/other.cjs b/api/testdata/tarballs/cjs_import/other.cjs
new file mode 100644
index 00000000..e89508f4
--- /dev/null
+++ b/api/testdata/tarballs/cjs_import/other.cjs
@@ -0,0 +1 @@
+exports.test = "test";
diff --git a/frontend/docs/troubleshooting.md b/frontend/docs/troubleshooting.md
index 5e07e445..4adf704f 100644
--- a/frontend/docs/troubleshooting.md
+++ b/frontend/docs/troubleshooting.md
@@ -91,8 +91,9 @@ source.
 
 ### `commonJs`
 
-The package being published contains CommonJS code like `require()`. This is
-disallowed because JSR is ESM only.
+The package being published imports code from CommonJS files with a `.cjs` or
+`.cts` extension or contains CommonJS code like `require()`. This is disallowed
+because JSR is ESM only.
 
 You can fix this error by removing the CommonJS code from your source.