diff --git a/src/libraries/System.Reflection.Metadata/ref/System.Reflection.Metadata.cs b/src/libraries/System.Reflection.Metadata/ref/System.Reflection.Metadata.cs
index 8fd0fdbc5e3868..7127f8b68eb6cf 100644
--- a/src/libraries/System.Reflection.Metadata/ref/System.Reflection.Metadata.cs
+++ b/src/libraries/System.Reflection.Metadata/ref/System.Reflection.Metadata.cs
@@ -3132,6 +3132,7 @@ public readonly partial struct VectorEncoder
 }
 namespace System.Reflection.PortableExecutable
 {
+    [System.FlagsAttribute]
     public enum Characteristics : ushort
     {
         RelocsStripped = (ushort)1,
diff --git a/src/libraries/System.Reflection.Metadata/src/System/Reflection/PortableExecutable/PEFileFlags.cs b/src/libraries/System.Reflection.Metadata/src/System/Reflection/PortableExecutable/PEFileFlags.cs
index dc4b8dc3949daf..7311e5f6d9f50b 100644
--- a/src/libraries/System.Reflection.Metadata/src/System/Reflection/PortableExecutable/PEFileFlags.cs
+++ b/src/libraries/System.Reflection.Metadata/src/System/Reflection/PortableExecutable/PEFileFlags.cs
@@ -4,6 +4,7 @@
 
 namespace System.Reflection.PortableExecutable
 {
+    [Flags]
     public enum Characteristics : ushort
     {
         RelocsStripped = 0x0001,         // Relocation info stripped from file.