diff --git a/src/mono/sample/wasm/browser-bench/Span.cs b/src/mono/sample/wasm/browser-bench/Span.cs
index 2317820c2daeaa..ecd18ac2775618 100644
--- a/src/mono/sample/wasm/browser-bench/Span.cs
+++ b/src/mono/sample/wasm/browser-bench/Span.cs
@@ -19,6 +19,7 @@ public SpanTask()
                 new ReverseChar(),
                 new IndexOfByte(),
                 new IndexOfChar(),
+                new IndexOfString(),
                 new SequenceEqualByte(),
                 new SequenceEqualChar(),
             };
@@ -83,6 +84,22 @@ public override void RunStep()
             }
         }
 
+        class IndexOfString : SpanMeasurement
+        {
+            public override string Name => "IndexOf strings";
+
+            string input = "string1";
+            string value = "string2";
+
+            public override void RunStep()
+            {
+                ReadOnlySpan<char> inputSpan = input.AsSpan();
+                ReadOnlySpan<char> valueSpan = value.AsSpan();
+
+                inputSpan.IndexOf(valueSpan, StringComparison.InvariantCulture);
+            }
+        }
+
         abstract class SpanCharMeasurement : SpanMeasurement
         {
             protected char[] data;