diff --git a/Assets/Ros2ForUnity/Scripts/Time/DotnetTimeSource.cs b/Assets/Ros2ForUnity/Scripts/Time/DotnetTimeSource.cs
index 5fa9e99e4..cfc0dfe25 100644
--- a/Assets/Ros2ForUnity/Scripts/Time/DotnetTimeSource.cs
+++ b/Assets/Ros2ForUnity/Scripts/Time/DotnetTimeSource.cs
@@ -22,6 +22,7 @@ namespace ROS2
 /// DateTime based clock that has resolution increased using Stopwatch.
 /// DateTime is used to synchronize since Stopwatch tends to drift.
 /// </summary>
+[System.Obsolete("This TimeSource is deprecated and will be removed in the future versions. Please use DotNetSystemTimeSource instead.")]
 public class DotnetTimeSource : ITimeSource
 {
     private readonly double maxUnsyncedSeconds = 10;
diff --git a/Assets/Ros2ForUnity/Scripts/Time/ROS2ScalableTimeSource.cs b/Assets/Ros2ForUnity/Scripts/Time/ROS2ScalableTimeSource.cs
index 6c7c129ee..065d4141d 100644
--- a/Assets/Ros2ForUnity/Scripts/Time/ROS2ScalableTimeSource.cs
+++ b/Assets/Ros2ForUnity/Scripts/Time/ROS2ScalableTimeSource.cs
@@ -21,6 +21,7 @@ namespace ROS2
 /// <summary>
 /// ros2 time source (system time by default).
 /// </summary>
+[System.Obsolete("This TimeSource is deprecated and will be removed in the future versions. Please use DotNetSystemTimeSource instead.")]
 public class ROS2ScalableTimeSource : ITimeSource
 {
   private Thread mainThread;