diff --git a/src/cpu/core_normal/prefix_0f.h b/src/cpu/core_normal/prefix_0f.h
index 1292396f..ff809886 100644
--- a/src/cpu/core_normal/prefix_0f.h
+++ b/src/cpu/core_normal/prefix_0f.h
@@ -377,7 +377,7 @@
 					SaveMb(eaa,*rmrb);
 					SETFLAGBIT(ZF,1);
 				} else {
-					SaveMb(eaa,val); //NEEDED ? (val doesn't change
+					SaveMb(eaa,val);	// cmpxchg always issues a write
 					reg_al = val;
 					SETFLAGBIT(ZF,0);
 				}
@@ -405,7 +405,7 @@
 					SaveMw(eaa,*rmrw);
 					SETFLAGBIT(ZF,1);
 				} else {
-					SaveMw(eaa,val);
+					SaveMw(eaa,val);	// cmpxchg always issues a write
 					reg_ax = val;
 					SETFLAGBIT(ZF,0);
 				}
diff --git a/src/cpu/core_normal/prefix_66_0f.h b/src/cpu/core_normal/prefix_66_0f.h
index f2180309..1563050b 100644
--- a/src/cpu/core_normal/prefix_66_0f.h
+++ b/src/cpu/core_normal/prefix_66_0f.h
@@ -256,7 +256,7 @@
 					SaveMd(eaa,*rmrd);
 					SETFLAGBIT(ZF,1);
 				} else {
-					SaveMd(eaa,val);
+					SaveMd(eaa,val);	// cmpxchg always issues a write
 					reg_eax=val;
 					SETFLAGBIT(ZF,0);
 				}