diff --git a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs
index c6913ba2e5208b9567272d1b874002d48e4d29fa..9d9fa34a2fba55b8914b1b5f88e6cb90547d5aff 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs
@@ -1696,9 +1696,16 @@ private static Guid GenerateGuidFromName(string name)
                     {
                         dataType = Enum.GetUnderlyingType(dataType);
 
-                        int dataTypeSize = System.Runtime.InteropServices.Marshal.SizeOf(dataType);
-                        if (dataTypeSize < sizeof(int))
-                            dataType = typeof(int);
+                        // Enums less than 4 bytes in size should be treated as int.
+                        switch (Type.GetTypeCode(dataType))
+                        {
+                            case TypeCode.Byte:
+                            case TypeCode.SByte:
+                            case TypeCode.Int16:
+                            case TypeCode.UInt16:
+                                dataType = typeof(int);
+                                break;
+                        }
                         goto Again;
                     }