diff --git a/packages/protobuf-test/src/descriptor-set.test.ts b/packages/protobuf-test/src/descriptor-set.test.ts
index 4974baf31..717d16f5e 100644
--- a/packages/protobuf-test/src/descriptor-set.test.ts
+++ b/packages/protobuf-test/src/descriptor-set.test.ts
@@ -29,6 +29,7 @@ import {
   TestAllExtensions,
   TestNestedExtension,
 } from "./gen/ts/google/protobuf/unittest_pb.js";
+import { UpstreamProtobuf } from "upstream-protobuf";
 
 const fdsBytes = readFileSync("./descriptorset.bin");
 
@@ -54,6 +55,50 @@ describe("DescriptorSet", () => {
     expect(descFile?.syntax).toBe("editions");
     expect(descFile?.edition).toBe(Edition.EDITION_2023);
   });
+  describe("repeated field packing", () => {
+    test("proto2 is unpacked by default", async () => {
+      const bin = await new UpstreamProtobuf().compileToDescriptorSet(`
+        syntax="proto2";
+        message M {
+          optional int32 not_packable = 1;
+          repeated bytes also_not_packable = 2;
+          repeated int32 default = 3;
+          repeated int32 explicitly_packed = 4 [packed = true];
+          repeated int32 explicitly_expanded = 5 [packed = false];
+        }
+      `);
+      const fields = createDescriptorSet(bin).messages.get("M")?.fields;
+      expect(fields?.[0].packedByDefault).toBe(false);
+      expect(fields?.[1].packedByDefault).toBe(false);
+      expect(fields?.[2].packedByDefault).toBe(false);
+      expect(fields?.[0].packed).toBe(false);
+      expect(fields?.[1].packed).toBe(false);
+      expect(fields?.[2].packed).toBe(false);
+      expect(fields?.[3].packed).toBe(true);
+      expect(fields?.[4].packed).toBe(false);
+    });
+    test("proto3 is packed by default", async () => {
+      const bin = await new UpstreamProtobuf().compileToDescriptorSet(`
+        syntax="proto3";
+        message M {
+          int32 not_packable = 1;
+          repeated bytes also_not_packable = 2;
+          repeated int32 default = 3;
+          repeated int32 explicitly_packed = 4 [packed = true];
+          repeated int32 explicitly_expanded = 5 [packed = false];
+        }
+      `);
+      const fields = createDescriptorSet(bin).messages.get("M")?.fields;
+      expect(fields?.[0].packedByDefault).toBe(true);
+      expect(fields?.[1].packedByDefault).toBe(false);
+      expect(fields?.[2].packedByDefault).toBe(true);
+      expect(fields?.[0].packed).toBe(true);
+      expect(fields?.[1].packed).toBe(false);
+      expect(fields?.[2].packed).toBe(true);
+      expect(fields?.[3].packed).toBe(true);
+      expect(fields?.[4].packed).toBe(false);
+    });
+  });
   test("knows extension", () => {
     const ext = set.extensions.get(
       "protobuf_unittest.optional_int32_extension",
diff --git a/packages/upstream-protobuf/index.d.ts b/packages/upstream-protobuf/index.d.ts
index 0d0e71577..861cdef2d 100644
--- a/packages/upstream-protobuf/index.d.ts
+++ b/packages/upstream-protobuf/index.d.ts
@@ -22,5 +22,16 @@ export declare class UpstreamProtobuf {
     maximumEdition?: string,
   ): Promise<Uint8Array>;
 
-  compileToDescriptorSet(files: Record<string, string>): Promise<Uint8Array>;
+  compileToDescriptorSet(
+    fileContent: string,
+    opt?: CompileToDescriptorSetOptions,
+  ): Promise<Uint8Array>;
+  compileToDescriptorSet(
+    files: Record<string, string>,
+    opt?: CompileToDescriptorSetOptions,
+  ): Promise<Uint8Array>;
+}
+
+interface CompileToDescriptorSetOptions {
+  includeSourceInfo?: boolean;
 }
diff --git a/packages/upstream-protobuf/index.mjs b/packages/upstream-protobuf/index.mjs
index 6b21f66e9..212ceaafd 100644
--- a/packages/upstream-protobuf/index.mjs
+++ b/packages/upstream-protobuf/index.mjs
@@ -121,31 +121,40 @@ export class UpstreamProtobuf {
   }
 
   /**
-   * @param {Record<string, string>} files
+   * @typedef CompileToDescriptorSetOptions
+   * @property {boolean} [includeSourceInfo]
+   */
+  /**
+   * @param {Record<string, string>|string} filesOrFileContent
+   * @param {CompileToDescriptorSetOptions} [opt]
    * @return {Promise<Buffer>}
    */
-  async compileToDescriptorSet(files) {
+  async compileToDescriptorSet(filesOrFileContent, opt) {
     const protocPath = await this.getProtocPath();
     const tempDir = mkdtempSync(
       joinPath(this.#temp, "compile-descriptor-set-"),
     );
+    const files =
+      typeof filesOrFileContent == "string"
+        ? { "input.proto": filesOrFileContent }
+        : filesOrFileContent;
     try {
       writeTree(Object.entries(files), tempDir);
       const outPath = joinPath(tempDir, "desc.bin");
-      execFileSync(
-        protocPath,
-        [
-          "--descriptor_set_out",
-          outPath,
-          "--proto_path",
-          tempDir,
-          ...Object.keys(files),
-        ],
-        {
-          shell: false,
-          stdio: "ignore",
-        },
-      );
+      const args = [
+        "--experimental_editions",
+        "--descriptor_set_out",
+        outPath,
+        "--proto_path",
+        tempDir,
+        ...Object.keys(files),
+      ];
+      if (opt?.includeSourceInfo) {
+        args.unshift("--include_source_info");
+      }
+      execFileSync(protocPath, args, {
+        shell: false,
+      });
       return readFileSync(outPath);
     } finally {
       rmSync(tempDir, { recursive: true });