diff --git a/requirements/audio.txt b/requirements/audio.txt
index e3d50b57..f0fdb054 100644
--- a/requirements/audio.txt
+++ b/requirements/audio.txt
@@ -9,8 +9,8 @@ lxml
 matplotlib
 nara_wpe
 numpy<=1.18
-# tested on version before 3.20, expecting no breaking change going forward
-protobuf>3
+# protobuf version beyond 3.20.0 is not compatible with TensorFlow 1.x, therefore is discouraged.
+protobuf>3,<3.21.0
 ptflops
 pytorch_wavelets
 PyWavelets>=1.0.0
diff --git a/requirements/runtime.txt b/requirements/runtime.txt
index 9b133548..9ced1dfc 100644
--- a/requirements/runtime.txt
+++ b/requirements/runtime.txt
@@ -6,8 +6,6 @@ filelock>=3.3.0
 numpy
 opencv-python
 Pillow>=6.2.0
-# tested on version before 3.20, expecting no breaking change going forward
-protobuf>3
 pyyaml
 requests
 scipy
diff --git a/tests/run.py b/tests/run.py
index eaa45f60..27af7fe5 100644
--- a/tests/run.py
+++ b/tests/run.py
@@ -49,7 +49,9 @@ def main(args):
     if not args.list_tests:
         result = runner.run(test_suite)
         if len(result.failures) > 0:
-            sys.exit(1)
+            sys.exit(len(result.failures))
+        if len(result.errors) > 0:
+            sys.exit(len(result.errors))
 
 
 if __name__ == '__main__':