diff --git a/mps/code/mpmst.h b/mps/code/mpmst.h
index d435ee87870..479836e8b5b 100644
--- a/mps/code/mpmst.h
+++ b/mps/code/mpmst.h
@@ -83,7 +83,7 @@ typedef struct mps_pool_class_s {
 
 typedef struct mps_pool_s {     /* generic structure */
   InstStruct instStruct;
-  Sig sig;                      /* design.mps.sig.field [FIXME: Why is this not at the end? RB 2023-03-09] */
+  Sig sig;                      /* design.mps.sig.field */
   Serial serial;                /* from arena->poolSerial */
   Arena arena;                  /* owning arena */
   RingStruct arenaRing;         /* link in list of pools in arena */
@@ -218,7 +218,7 @@ typedef struct SegClassStruct {
 
 typedef struct SegStruct {      /* segment structure */
   InstStruct instStruct;
-  Sig sig;                      /* design.mps.sig.field [FIXME: should be at end?  RB 2023-03-09] */
+  Sig sig;                      /* design.mps.sig.field */
   Tract firstTract;             /* first tract of segment */
   RingStruct poolRing;          /* link in list of segs in pool */
   Addr limit;                   /* limit of segment */
@@ -307,7 +307,7 @@ typedef struct BufferClassStruct {
 
 typedef struct BufferStruct {
   InstStruct instStruct;
-  Sig sig;                      /* design.mps.sig.field [FIXME: Why is this not at the end?  RB 2023-03-09] */
+  Sig sig;                      /* design.mps.sig.field */
   Serial serial;                /* from pool->bufferSerial */
   Arena arena;                  /* owning arena */
   Pool pool;                    /* owning pool */
diff --git a/mps/code/protocol.h b/mps/code/protocol.h
index 4ea07a58f97..c13bafcd9c7 100644
--- a/mps/code/protocol.h
+++ b/mps/code/protocol.h
@@ -186,7 +186,7 @@ typedef void (*FinishMethod)(Inst inst);
 
 typedef struct InstClassStruct {
   InstStruct instStruct;        /* classes are instances of kinds */
-  Sig sig;                      /* design.mps.sig.field [FIXME: Why isn't this at the end? RB 2023-03-09] */
+  Sig sig;                      /* design.mps.sig.field */
   ClassName name;               /* human readable name such as "Land" */
   InstClass superclass;         /* pointer to direct superclass */
   ClassLevel level;             /* distance from root of class hierarchy */