diff --git a/server/requirements.txt b/server/requirements.txt
index a1ef52ec..b228e7bf 100644
--- a/server/requirements.txt
+++ b/server/requirements.txt
@@ -7,6 +7,6 @@ elasticsearch>=5.0.0
 elasticsearch-dsl>=5.0.0
 numpy>=1.8.2
 pillow>=4.3.0
-pynacl>=1.2.1
+pynacl==1.2.1
 pytz>=2018.3
 pyRFC3339>=1.0
diff --git a/server/szurubooru/func/images.py b/server/szurubooru/func/images.py
index 4dce5d86..19cd8a42 100644
--- a/server/szurubooru/func/images.py
+++ b/server/szurubooru/func/images.py
@@ -158,7 +158,7 @@ class Image:
             '-af', 'volumedetect',
             '-f', 'null',
             '-y', '/dev/null',
-        ], get_logs=True).decode('utf-8')
+        ], get_logs=True).decode('utf-8', errors='replace')
         log_match = re.search(r'.*volumedetect.*mean_volume: (.*) dB', log)
         assert log_match
         assert log_match.groups()