diff --git a/pkgs/firehose/CHANGELOG.md b/pkgs/firehose/CHANGELOG.md
index d8da3b02..9711bd9c 100644
--- a/pkgs/firehose/CHANGELOG.md
+++ b/pkgs/firehose/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.8.0
+
+- Only check text files for do not submit strings.
+
 ## 0.7.0
 
 - Add `ignore-packages` flag to the publish workflow.
diff --git a/pkgs/firehose/lib/src/health/health.dart b/pkgs/firehose/lib/src/health/health.dart
index 264f3589..dc9343d6 100644
--- a/pkgs/firehose/lib/src/health/health.dart
+++ b/pkgs/firehose/lib/src/health/health.dart
@@ -306,6 +306,8 @@ Changes to files need to be [accounted for](https://github.com/dart-lang/ecosyst
 
   Future<HealthCheckResult> doNotSubmitCheck() async {
     final dns = 'DO_NOT${'_'}SUBMIT';
+    // To avoid trying to read non-text files.
+    const supportedExtensions = ['.dart', '.json', '.md', '.txt'];
 
     final body = await github.pullrequestBody();
     final files = await github.listFilesForPR(directory, ignoredPackages);
@@ -313,6 +315,8 @@ Changes to files need to be [accounted for](https://github.com/dart-lang/ecosyst
     final filesWithDNS = files
         .where((file) =>
             ![FileStatus.removed, FileStatus.unchanged].contains(file.status))
+        .where((file) =>
+            supportedExtensions.contains(path.extension(file.filename)))
         .where((file) => File(file.pathInRepository)
             .readAsStringSync()
             .contains('DO_NOT${'_'}SUBMIT'))
diff --git a/pkgs/firehose/pubspec.yaml b/pkgs/firehose/pubspec.yaml
index baacac6c..89be06a4 100644
--- a/pkgs/firehose/pubspec.yaml
+++ b/pkgs/firehose/pubspec.yaml
@@ -1,6 +1,6 @@
 name: firehose
 description: A tool to automate publishing of Pub packages from GitHub actions.
-version: 0.7.0
+version: 0.8.0
 repository: https://github.com/dart-lang/ecosystem/tree/main/pkgs/firehose
 
 environment:
diff --git a/pkgs/firehose/test/health_test.dart b/pkgs/firehose/test/health_test.dart
index 33025f66..41f408ec 100644
--- a/pkgs/firehose/test/health_test.dart
+++ b/pkgs/firehose/test/health_test.dart
@@ -25,6 +25,11 @@ Future<void> main() async {
       FileStatus.added,
       directory,
     ),
+    GitFile(
+      'pkgs/package2/someImage.png',
+      FileStatus.added,
+      directory,
+    ),
   ]);
   await Process.run('dart', ['pub', 'global', 'activate', 'dart_apitool']);
   await Process.run('dart', ['pub', 'global', 'activate', 'coverage']);
diff --git a/pkgs/firehose/test_data/test_repo/pkgs/package2/someImage.png b/pkgs/firehose/test_data/test_repo/pkgs/package2/someImage.png
new file mode 100644
index 00000000..7f81c472
Binary files /dev/null and b/pkgs/firehose/test_data/test_repo/pkgs/package2/someImage.png differ