diff --git a/__tests__/main.test.ts b/__tests__/main.test.ts
index bd4f6cd1a..6b10904cb 100644
--- a/__tests__/main.test.ts
+++ b/__tests__/main.test.ts
@@ -313,6 +313,15 @@ describe('run', () => {
     );
   });
 
+  it('does not add labels to PRs that have no changed files', async () => {
+    usingLabelerConfigYaml('only_pdfs.yml');
+    mockGitHubResponseChangedFiles();
+
+    await run();
+
+    expect(setLabelsMock).toHaveBeenCalledTimes(0);
+  });
+
   it('should use local configuration file if it exists', async () => {
     const configFile = 'only_pdfs.yml';
     const configFilePath = path.join(__dirname, 'fixtures', configFile);
diff --git a/dist/index.js b/dist/index.js
index 50da5bd83..5cb19babf 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -81,6 +81,10 @@ function run() {
                 }
                 core.debug(`fetching changed files for pr #${prNumber}`);
                 const changedFiles = yield getChangedFiles(client, prNumber);
+                if (!changedFiles.length) {
+                    core.warning(`Pull request #${prNumber} has no changed files, skipping`);
+                    continue;
+                }
                 const labelGlobs = yield getLabelGlobs(client, configPath);
                 const preexistingLabels = pullRequest.labels.map(l => l.name);
                 const allLabels = new Set(preexistingLabels);
diff --git a/src/labeler.ts b/src/labeler.ts
index 8893a81e5..995abaa35 100644
--- a/src/labeler.ts
+++ b/src/labeler.ts
@@ -48,6 +48,13 @@ export async function run() {
 
       core.debug(`fetching changed files for pr #${prNumber}`);
       const changedFiles: string[] = await getChangedFiles(client, prNumber);
+      if (!changedFiles.length) {
+        core.warning(
+          `Pull request #${prNumber} has no changed files, skipping`
+        );
+        continue;
+      }
+
       const labelGlobs: Map<string, StringOrMatchConfig[]> =
         await getLabelGlobs(client, configPath);