diff --git a/packages/repo-tools/src/commands/index.ts b/packages/repo-tools/src/commands/index.ts
index 6a557d909e..3fa16aa512 100644
--- a/packages/repo-tools/src/commands/index.ts
+++ b/packages/repo-tools/src/commands/index.ts
@@ -83,6 +83,7 @@ function registerPackageCommand(program: Command) {
     .command('check')
     .option('--ignore', 'Ignore linting failures and only log the results.')
     .option('--json', 'Output the results as JSON')
+    .option('--since <ref>', 'Check the API against a specific ref')
     .action(
       lazy(() => import('./package/schema/openapi/check').then(m => m.command)),
     );
diff --git a/packages/repo-tools/src/commands/package/schema/openapi/check.ts b/packages/repo-tools/src/commands/package/schema/openapi/check.ts
index 22d2d0a0d6..3cb0baf313 100644
--- a/packages/repo-tools/src/commands/package/schema/openapi/check.ts
+++ b/packages/repo-tools/src/commands/package/schema/openapi/check.ts
@@ -32,7 +32,7 @@ const reduceOpticOutput = (output: string) => {
 async function check(opts: OptionValues) {
   const resolvedOpenapiPath = await getPathToCurrentOpenApiSpec();
 
-  let baseRef = opts.since ?? process.env.GITHUB_BASE_REF;
+  let baseRef = opts.since;
   if (!baseRef) {
     const { stdout: branch } = await exec(
       'git merge-base --fork-point origin/master',
diff --git a/packages/repo-tools/src/commands/repo/schema/openapi/check.ts b/packages/repo-tools/src/commands/repo/schema/openapi/check.ts
index f77586a840..41d0bec0e5 100644
--- a/packages/repo-tools/src/commands/repo/schema/openapi/check.ts
+++ b/packages/repo-tools/src/commands/repo/schema/openapi/check.ts
@@ -47,9 +47,10 @@ export async function command(opts: OptionValues) {
       severity: 0,
     } as CiRunDetails;
     for (const pkg of checkablePackages) {
+      const baseRef = opts.since ?? process.env.GITHUB_BASE_REF;
       const { stdout } = await exec(
         'yarn',
-        ['check:api', '--ignore', '--json'],
+        ['check:api', '--ignore', '--json', '--since', baseRef],
         {
           cwd: pkg.dir,
         },