diff --git a/src/libraries/System.Text.Json/ref/System.Text.Json.cs b/src/libraries/System.Text.Json/ref/System.Text.Json.cs
index b81b745471f18..c0f23522b137d 100644
--- a/src/libraries/System.Text.Json/ref/System.Text.Json.cs
+++ b/src/libraries/System.Text.Json/ref/System.Text.Json.cs
@@ -978,7 +978,7 @@ public enum JsonKnownNamingPolicy
         KebabCaseLower = 4,
         KebabCaseUpper = 5,
     }
-    public sealed partial class JsonNumberEnumConverter<TEnum> : System.Text.Json.Serialization.JsonConverterFactory where TEnum : struct
+    public sealed partial class JsonNumberEnumConverter<TEnum> : System.Text.Json.Serialization.JsonConverterFactory where TEnum : struct, System.Enum
     {
         public JsonNumberEnumConverter() { }
         public override bool CanConvert(System.Type typeToConvert) { throw null; }