diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/RuntimeEventSource.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/RuntimeEventSource.cs
index 336e981bd622ae..4086fa0491ccdb 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/RuntimeEventSource.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/RuntimeEventSource.cs
@@ -35,6 +35,7 @@ internal sealed class RuntimeEventSource : EventSource
         private PollingCounter? _gen1SizeCounter;
         private PollingCounter? _gen2SizeCounter;
         private PollingCounter? _lohSizeCounter;
+        private PollingCounter? _pohSizeCounter;
         private PollingCounter? _assemblyCounter;
 #endif
 
@@ -76,6 +77,7 @@ protected override void OnEventCommand(EventCommandEventArgs command)
                 _gen1SizeCounter ??= new PollingCounter("gen-1-size", this, () => GC.GetGenerationSize(1)) { DisplayName = "Gen 1 Size", DisplayUnits = "B" };
                 _gen2SizeCounter ??= new PollingCounter("gen-2-size", this, () => GC.GetGenerationSize(2)) { DisplayName = "Gen 2 Size", DisplayUnits = "B" };
                 _lohSizeCounter ??= new PollingCounter("loh-size", this, () => GC.GetGenerationSize(3)) { DisplayName = "LOH Size", DisplayUnits = "B" };
+                _pohSizeCounter ??= new PollingCounter("poh-size", this, () => GC.GetGenerationSize(4)) { DisplayName = "POH (Pinned Object Heap) Size", DisplayUnits = "B" };
                 _assemblyCounter ??= new PollingCounter("assembly-count", this, () => System.Reflection.Assembly.GetAssemblyCount()) { DisplayName = "Number of Assemblies Loaded" };
 #endif
             }