diff --git a/src/hotspot/cpu/s390/c2_MacroAssembler_s390.cpp b/src/hotspot/cpu/s390/c2_MacroAssembler_s390.cpp
index 957c89af3fc..3bf9ab8dd82 100644
--- a/src/hotspot/cpu/s390/c2_MacroAssembler_s390.cpp
+++ b/src/hotspot/cpu/s390/c2_MacroAssembler_s390.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2026, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2017, 2024 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -42,10 +42,12 @@ void C2_MacroAssembler::fast_unlock(Register obj, Register box, Register temp1,
 }
 
 void C2_MacroAssembler::load_narrow_klass_compact_c2(Register dst, Address src) {
+  BLOCK_COMMENT("load_narrow_klass_compact_c2 {");
   // The incoming address is pointing into obj-start + klass_offset_in_bytes. We need to extract
   // obj-start, so that we can load from the object's mark-word instead.
   z_lg(dst, src.plus_disp(-oopDesc::klass_offset_in_bytes()));
-  z_srlg(dst, dst, markWord::klass_shift); // TODO: could be z_sra
+  z_srlg(dst, dst, markWord::klass_shift);
+  BLOCK_COMMENT("} load_narrow_klass_compact_c2");
 }
 
 //------------------------------------------------------
diff --git a/src/hotspot/cpu/s390/s390.ad b/src/hotspot/cpu/s390/s390.ad
index 5f33cf4fa77..3d4abea7529 100644
--- a/src/hotspot/cpu/s390/s390.ad
+++ b/src/hotspot/cpu/s390/s390.ad
@@ -4816,17 +4816,15 @@ instruct loadNKlass(iRegN dst, memory mem) %{
   ins_pipe(pipe_class_dummy);
 %}
 
-instruct loadNKlassCompactHeaders(iRegN dst, memory mem, flagsReg cr) %{
+instruct loadNKlassCompactHeaders(iRegN dst, memory mem) %{
   match(Set dst (LoadNKlass mem));
   predicate(UseCompactObjectHeaders);
-  effect(KILL cr);
   ins_cost(MEMORY_REF_COST);
   format %{ "load_narrow_klass_compact $dst,$mem \t# compressed class ptr" %}
-  // TODO: size()
+  // z_lg (6 bytes) + z_srlg (6 bytes); neither instruction modifies the CC.
+  size(12);
   ins_encode %{
-    __ block_comment("load_narrow_klass_compact_c2 {");
     __ load_narrow_klass_compact_c2($dst$$Register, $mem$$Address);
-    __ block_comment("} load_narrow_klass_compact");
   %}
   ins_pipe(pipe_class_dummy);
 %}