diff --git a/src/arch/x86_64/bits.zig b/src/arch/x86_64/bits.zig
index 04b21b9e21c8fbee539e068718e416f8fa03cf7e..a640853d5deeedb013d97dd508eed3e96bac6a3f 100644
--- a/src/arch/x86_64/bits.zig
+++ b/src/arch/x86_64/bits.zig
@@ -384,7 +384,7 @@ test "Register id - different classes" {
     try expect(Register.xmm0.id() != Register.mm0.id());
     try expect(Register.mm0.id() != Register.st0.id());
 
-    try expect(Register.es.id() == 0b100000);
+    try expect(Register.es.id() == 0b110000);
 }
 
 test "Register enc - different classes" {