diff --git a/lib/ref/mime_types.dart b/lib/ref/mime_types.dart
index 978668f31..185165bec 100644
--- a/lib/ref/mime_types.dart
+++ b/lib/ref/mime_types.dart
@@ -111,5 +111,6 @@ class MimeTypes {
       case '.svg':
         return svg;
     }
+    return null;
   }
 }
diff --git a/lib/utils/time_utils.dart b/lib/utils/time_utils.dart
index b3699462f..f448aef68 100644
--- a/lib/utils/time_utils.dart
+++ b/lib/utils/time_utils.dart
@@ -36,6 +36,7 @@ DateTime? dateTimeFromMillis(int? millis, {bool isUtc = false}) {
     millis = int.tryParse('$millis'.substring(0, _millisMaxDigits));
     return dateTimeFromMillis(millis, isUtc: isUtc);
   }
+  return null;
 }
 
 final _unixStampMillisPattern = RegExp(r'\d{13}');
@@ -93,4 +94,6 @@ DateTime? parseUnknownDateFormat(String? s) {
       }
     }
   }
+
+  return null;
 }
diff --git a/lib/utils/xmp_utils.dart b/lib/utils/xmp_utils.dart
index d897e476a..88e153dd4 100644
--- a/lib/utils/xmp_utils.dart
+++ b/lib/utils/xmp_utils.dart
@@ -283,6 +283,7 @@ class XMP {
       case -1:
         return '-1';
     }
+    return null;
   }
 }