diff --git a/mcs/tools/linker/Mono.Linker.Steps/MarkStep.cs b/mcs/tools/linker/Mono.Linker.Steps/MarkStep.cs
index bd55c8527c6d154f2b16908a6a7d4c3144eb83d9..74c219a82b61bd5811c3b708350b6a85a7c19a92 100644
--- a/mcs/tools/linker/Mono.Linker.Steps/MarkStep.cs
+++ b/mcs/tools/linker/Mono.Linker.Steps/MarkStep.cs
@@ -336,6 +336,9 @@ namespace Mono.Linker.Steps {
 					return;
 
 				MarkType (et);
+				if (argument.Value == null)
+					return;
+
 				foreach (var cac in (CustomAttributeArgument[]) argument.Value)
 					MarkWithResolvedScope ((TypeReference) cac.Value);
 			} else if (at.Namespace == "System" && at.Name == "Type") {