diff --git a/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowBuilderExtensions.cs b/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowBuilderExtensions.cs
index c261036c6b..e7f68e4f69 100644
--- a/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowBuilderExtensions.cs
+++ b/dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowBuilderExtensions.cs
@@ -128,9 +128,16 @@ public static class WorkflowBuilderExtensions
         Throw.IfNull(targets);
 
         List<ExecutorBinding> targetList = [];
-        int targetIndex = 0;
-        foreach (ExecutorBinding? target in targets)
+        using IEnumerator<ExecutorBinding> targetEnumerator = targets.GetEnumerator();
+        if (!targetEnumerator.MoveNext())
         {
+            throw new ArgumentException("Targets collection cannot be empty.", nameof(targets));
+        }
+
+        int targetIndex = 0;
+        do
+        {
+            ExecutorBinding? target = targetEnumerator.Current;
             if (target is null)
             {
                 throw new ArgumentNullException(nameof(targets), $"Targets collection contains a null element at index {targetIndex}.");
@@ -139,8 +146,8 @@ public static class WorkflowBuilderExtensions
             targetList.Add(target);
             targetIndex++;
         }
+        while (targetEnumerator.MoveNext());
 
-        Throw.IfNullOrEmpty(targetList, nameof(targets));
         return targetList;
     }
 
diff --git a/dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowBuilderSmokeTests.cs b/dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowBuilderSmokeTests.cs
index 27bbb1092c..4e9cb19ee3 100644
--- a/dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowBuilderSmokeTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowBuilderSmokeTests.cs
@@ -396,6 +396,7 @@ public partial class WorkflowBuilderSmokeTests
         WorkflowBuilder builder = new("start");
         NoOpExecutor source = new("start");
         NoOpExecutor target = new("target");
+        NoOpExecutor otherTarget = new("other-target");
 
         // Act/Assert
         Assert.Throws<ArgumentNullException>("builder", () => ((WorkflowBuilder)null!).AddChain(source, [target]));
@@ -403,6 +404,7 @@ public partial class WorkflowBuilderSmokeTests
         Assert.Throws<ArgumentNullException>("executors", () => builder.AddChain(source, null!));
         Assert.Throws<ArgumentNullException>("executors", () => builder.AddChain(source, [target, null!]));
         Assert.Throws<ArgumentException>("executors", () => builder.AddChain(source, [target, source]));
+        Assert.Throws<ArgumentException>("executors", () => builder.AddChain(source, [target, otherTarget, target]));
     }
 
     [Fact]