diff --git a/compiler/utils/jni_macro_assembler.cc b/compiler/utils/jni_macro_assembler.cc
index 797a98c..1b74313 100644
--- a/compiler/utils/jni_macro_assembler.cc
+++ b/compiler/utils/jni_macro_assembler.cc
@@ -99,6 +99,7 @@
       return MacroAsm64UniquePtr(new (arena) x86_64::X86_64JNIMacroAssembler(arena));
 #endif
     default:
+      UNUSED(arena);
       LOG(FATAL) << "Unknown/unsupported 8B InstructionSet: " << instruction_set;
       UNREACHABLE();
   }