diff --git a/src/hb-ot-cff-common-private.hh b/src/hb-ot-cff-common-private.hh
index 3e3ac36fc..92667653f 100644
--- a/src/hb-ot-cff-common-private.hh
+++ b/src/hb-ot-cff-common-private.hh
@@ -700,6 +700,28 @@ struct TableInfo
   unsigned int    size;
 };
 
+/* font dict index remap table from fullset FDArray to subset FDArray.
+ * set to HB_SET_VALUE_INVALID if excluded from subset */
+struct FDMap : hb_vector_t<hb_codepoint_t>
+{
+  inline void init (void)
+  { hb_vector_t<hb_codepoint_t>::init (); }
+
+  inline void fini (void)
+  { hb_vector_t<hb_codepoint_t>::fini (); }
+
+  inline bool fullset (void) const
+  {
+    for (unsigned int i = 0; i < len; i++)
+      if ((*this)[i] == HB_SET_VALUE_INVALID)
+        return false;
+    return true;
+  }
+
+  inline bool excludes (hb_codepoint_t fd) const
+  { return (fd < len) && ((*this)[fd] == HB_SET_VALUE_INVALID); }
+};
+
 template <typename COUNT>
 struct FDArray : IndexOf<COUNT, FontDict>
 {
@@ -708,7 +730,7 @@ struct FDArray : IndexOf<COUNT, FontDict>
                         unsigned int offSize_,
                         const hb_vector_t<DICTVAL> &fontDicts,
                         unsigned int fdCount,
-                        const hb_vector_t<hb_codepoint_t> &fdmap,
+                        const FDMap &fdmap,
                         OP_SERIALIZER& opszr,
                         const hb_vector_t<TableInfo> &privateInfos)
   {
@@ -723,7 +745,7 @@ struct FDArray : IndexOf<COUNT, FontDict>
     unsigned int  offset = 1;
     unsigned int  fid = 0;
     for (unsigned i = 0; i < fontDicts.len; i++)
-      if (!fdmap.len || fdmap[i] != HB_SET_VALUE_INVALID)
+      if (!fdmap.excludes (i))
       {
         IndexOf<COUNT, FontDict>::set_offset_at (fid++, offset);
         offset += FontDict::calculate_serialized_size (fontDicts[i], opszr);
@@ -732,10 +754,10 @@ struct FDArray : IndexOf<COUNT, FontDict>
 
     /* serialize font dicts */
     for (unsigned int i = 0; i < fontDicts.len; i++)
-      if (fdmap[i] != HB_SET_VALUE_INVALID)
+      if (!fdmap.excludes (i))
       {
         FontDict *dict = c->start_embed<FontDict> ();
-        if (unlikely (!dict->serialize (c, fontDicts[i], opszr, privateInfos[i])))
+        if (unlikely (!dict->serialize (c, fontDicts[i], opszr, privateInfos[fdmap[i]])))
           return_trace (false);
       }
     return_trace (true);
@@ -746,12 +768,12 @@ struct FDArray : IndexOf<COUNT, FontDict>
   inline static unsigned int calculate_serialized_size (unsigned int &offSize_ /* OUT */,
                                                         const hb_vector_t<DICTVAL> &fontDicts,
                                                         unsigned int fdCount,
-                                                        const hb_vector_t<hb_codepoint_t> &fdmap,
+                                                        const FDMap &fdmap,
                                                         OP_SERIALIZER& opszr)
   {
     unsigned int dictsSize = 0;
     for (unsigned int i = 0; i < fontDicts.len; i++)
-      if (!fdmap.len || fdmap[i] != HB_SET_VALUE_INVALID)
+      if (!fdmap.excludes (i))
         dictsSize += FontDict::calculate_serialized_size (fontDicts[i], opszr);
 
     offSize_ = calcOffSize (dictsSize + 1);
diff --git a/src/hb-subset-cff-common-private.cc b/src/hb-subset-cff-common-private.cc
index b74a298ee..6796709f0 100644
--- a/src/hb-subset-cff-common-private.cc
+++ b/src/hb-subset-cff-common-private.cc
@@ -46,7 +46,7 @@ hb_plan_subset_cff_fdselect (const hb_vector_t<hb_codepoint_t> &glyphs,
                             unsigned int &subst_fdselect_size /* OUT */,
                             unsigned int &subst_fdselect_format /* OUT */,
                             hb_vector_t<hb_codepoint_t> &subst_first_glyphs /* OUT */,
-                            hb_vector_t<hb_codepoint_t> &fdmap /* OUT */)
+                            FDMap &fdmap /* OUT */)
 {
   subset_fd_count = 0;
   subst_fdselect_size = 0;
@@ -131,7 +131,7 @@ serialize_fdselect_3_4 (hb_serialize_context_t *c,
                           const FDSelect &src,
                           unsigned int size,
                           const hb_vector_t<hb_codepoint_t> &first_glyphs,
-                          const hb_vector_t<hb_codepoint_t> &fdmap)
+                          const FDMap &fdmap)
 {
   TRACE_SERIALIZE (this);
   FDSELECT3_4 *p = c->allocate_size<FDSELECT3_4> (size);
@@ -159,7 +159,7 @@ hb_serialize_cff_fdselect (hb_serialize_context_t *c,
                           unsigned int fdselect_format,
                           unsigned int size,
                           const hb_vector_t<hb_codepoint_t> &first_glyphs,
-                          const hb_vector_t<hb_codepoint_t> &fdmap)
+                          const FDMap &fdmap)
 {
   TRACE_SERIALIZE (this);
   FDSelect  *p = c->allocate_min<FDSelect> ();
diff --git a/src/hb-subset-cff-common-private.hh b/src/hb-subset-cff-common-private.hh
index 97d5550fa..b1a743c10 100644
--- a/src/hb-subset-cff-common-private.hh
+++ b/src/hb-subset-cff-common-private.hh
@@ -39,7 +39,7 @@ hb_plan_subset_cff_fdselect (const hb_vector_t<hb_codepoint_t> &glyphs,
                             unsigned int &subst_fdselect_size /* OUT */,
                             unsigned int &subst_fdselect_format /* OUT */,
                             hb_vector_t<hb_codepoint_t> &subst_first_glyphs /* OUT */,
-                            hb_vector_t<hb_codepoint_t> &fdmap /* OUT */);
+                            CFF::FDMap &fdmap /* OUT */);
 
 HB_INTERNAL bool
 hb_serialize_cff_fdselect (hb_serialize_context_t *c,
@@ -49,6 +49,6 @@ hb_serialize_cff_fdselect (hb_serialize_context_t *c,
                           unsigned int fdselect_format,
                           unsigned int size,
                           const hb_vector_t<hb_codepoint_t> &first_glyphs,
-                          const hb_vector_t<hb_codepoint_t> &fdmap);
+                          const CFF::FDMap &fdmap);
 
 #endif /* HB_SUBSET_CFF_COMMON_PRIVATE_HH */
diff --git a/src/hb-subset-cff.cc b/src/hb-subset-cff.cc
index ea5066787..afc32f278 100644
--- a/src/hb-subset-cff.cc
+++ b/src/hb-subset-cff.cc
@@ -291,10 +291,13 @@ struct cff_subset_plan {
     offsets.privateDictInfo.offset = final_size;
     for (unsigned int i = 0; i < orig_fdcount; i++)
     {
-      CFFPrivateDict_OpSerializer privSzr;
-      TableInfo  privInfo = { final_size, PrivateDict::calculate_serialized_size (acc.privateDicts[i], privSzr) };
-      privateDictInfos.push (privInfo);
-      final_size += privInfo.size + acc.privateDicts[i].localSubrs->get_size ();
+      if (!fdmap.excludes (i))
+      {
+        CFFPrivateDict_OpSerializer privSzr;
+        TableInfo  privInfo = { final_size, PrivateDict::calculate_serialized_size (acc.privateDicts[i], privSzr) };
+        privateDictInfos.push (privInfo);
+        final_size += privInfo.size + acc.privateDicts[i].localSubrs->get_size ();
+      }
     }
 
     if (!acc.is_CID ())
@@ -317,7 +320,7 @@ struct cff_subset_plan {
 
   /* font dict index remap table from fullset FDArray to subset FDArray.
    * set to HB_SET_VALUE_INVALID if excluded from subset */
-  hb_vector_t<hb_codepoint_t>   fdmap;
+  FDMap   fdmap;
 
   hb_vector_t<ByteStr> subset_charstrings;
   hb_vector_t<TableInfo> privateDictInfos;
@@ -474,27 +477,30 @@ static inline bool _write_cff (const cff_subset_plan &plan,
   assert (plan.offsets.privateDictInfo.offset == c.head - c.start);
   for (unsigned int i = 0; i < acc.privateDicts.len; i++)
   {
-    PrivateDict  *pd = c.start_embed<PrivateDict> ();
-    if (unlikely (pd == nullptr)) return false;
-    CFFPrivateDict_OpSerializer privSzr;
-    /* N.B. local subrs immediately follows its corresponding private dict. i.e., subr offset == private dict size */
-    if (unlikely (!pd->serialize (&c, acc.privateDicts[i], privSzr, plan.privateDictInfos[i].size)))
+    if (!plan.fdmap.excludes (i))
     {
-      DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF Private Dict[%d]", i);
-      return false;
-    }
-    if (acc.privateDicts[i].subrsOffset != 0)
-    {
-      CFFSubrs *subrs = c.start_embed<CFFSubrs> ();
-      if (unlikely (subrs == nullptr) || acc.privateDicts[i].localSubrs == &Null(CFFSubrs))
+      PrivateDict  *pd = c.start_embed<PrivateDict> ();
+      if (unlikely (pd == nullptr)) return false;
+      CFFPrivateDict_OpSerializer privSzr;
+      /* N.B. local subrs immediately follows its corresponding private dict. i.e., subr offset == private dict size */
+      if (unlikely (!pd->serialize (&c, acc.privateDicts[i], privSzr, plan.privateDictInfos[plan.fdmap[i]].size)))
       {
-        DEBUG_MSG (SUBSET, nullptr, "CFF subset: local subrs unexpectedly null [%d]", i);
+        DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF Private Dict[%d]", i);
         return false;
       }
-      if (unlikely (!subrs->serialize (&c, *acc.privateDicts[i].localSubrs)))
+      if (acc.privateDicts[i].subrsOffset != 0)
       {
-        DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF local subrs [%d]", i);
-        return false;
+        CFFSubrs *subrs = c.start_embed<CFFSubrs> ();
+        if (unlikely (subrs == nullptr) || acc.privateDicts[i].localSubrs == &Null(CFFSubrs))
+        {
+          DEBUG_MSG (SUBSET, nullptr, "CFF subset: local subrs unexpectedly null [%d]", i);
+          return false;
+        }
+        if (unlikely (!subrs->serialize (&c, *acc.privateDicts[i].localSubrs)))
+        {
+          DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF local subrs [%d]", i);
+          return false;
+        }
       }
     }
   }
diff --git a/src/hb-subset-cff2.cc b/src/hb-subset-cff2.cc
index cd762dd81..418cdfb67 100644
--- a/src/hb-subset-cff2.cc
+++ b/src/hb-subset-cff2.cc
@@ -250,10 +250,13 @@ struct cff2_subset_plan {
     offsets.privateDictsOffset = final_size;
     for (unsigned int i = 0; i < orig_fdcount; i++)
     {
-      CFF2PrivateDict_OpSerializer privSzr;
-      TableInfo  privInfo = { final_size, PrivateDict::calculate_serialized_size (acc.privateDicts[i], privSzr) };
-      privateDictInfos.push (privInfo);
-      final_size += privInfo.size + acc.privateDicts[i].localSubrs->get_size ();
+      if (!fdmap.excludes (i))
+      {
+        CFF2PrivateDict_OpSerializer privSzr;
+        TableInfo  privInfo = { final_size, PrivateDict::calculate_serialized_size (acc.privateDicts[i], privSzr) };
+        privateDictInfos.push (privInfo);
+        final_size += privInfo.size + acc.privateDicts[i].localSubrs->get_size ();
+      }
     }
 
     return true;
@@ -270,9 +273,7 @@ struct cff2_subset_plan {
   unsigned int    subst_fdselect_format;
   hb_vector_t<hb_codepoint_t>   subst_fdselect_first_glyphs;
 
-  /* font dict index remap table from fullset FDArray to subset FDArray.
-   * set to HB_SET_VALUE_INVALID if excluded from subset */
-  hb_vector_t<hb_codepoint_t>   fdmap;
+  FDMap   fdmap;
 
   hb_vector_t<ByteStr> subset_charstrings;
   hb_vector_t<TableInfo> privateDictInfos;
@@ -390,27 +391,30 @@ static inline bool _write_cff2 (const cff2_subset_plan &plan,
   assert (plan.offsets.privateDictsOffset == c.head - c.start);
   for (unsigned int i = 0; i < acc.privateDicts.len; i++)
   {
-    PrivateDict  *pd = c.start_embed<PrivateDict> ();
-    if (unlikely (pd == nullptr)) return false;
-    CFF2PrivateDict_OpSerializer privSzr;
-    /* N.B. local subrs immediately follows its corresponding private dict. i.e., subr offset == private dict size */
-    if (unlikely (!pd->serialize (&c, acc.privateDicts[i], privSzr, plan.privateDictInfos[i].size)))
+    if (!plan.fdmap.excludes (i))
     {
-      DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF2 Private Dict[%d]", i);
-      return false;
-    }
-    if (acc.privateDicts[i].subrsOffset != 0)
-    {
-      CFF2Subrs *subrs = c.start_embed<CFF2Subrs> ();
-      if (unlikely (subrs == nullptr) || acc.privateDicts[i].localSubrs == &Null(CFF2Subrs))
+      PrivateDict  *pd = c.start_embed<PrivateDict> ();
+      if (unlikely (pd == nullptr)) return false;
+      CFF2PrivateDict_OpSerializer privSzr;
+      /* N.B. local subrs immediately follows its corresponding private dict. i.e., subr offset == private dict size */
+      if (unlikely (!pd->serialize (&c, acc.privateDicts[i], privSzr, plan.privateDictInfos[plan.fdmap[i]].size)))
       {
-        DEBUG_MSG (SUBSET, nullptr, "CFF2 subset: local subrs unexpectedly null [%d]", i);
+        DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF2 Private Dict[%d]", i);
         return false;
       }
-      if (unlikely (!subrs->serialize (&c, *acc.privateDicts[i].localSubrs)))
+      if (acc.privateDicts[i].subrsOffset != 0)
       {
-        DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF2 local subrs [%d]", i);
-        return false;
+        CFF2Subrs *subrs = c.start_embed<CFF2Subrs> ();
+        if (unlikely (subrs == nullptr) || acc.privateDicts[i].localSubrs == &Null(CFF2Subrs))
+        {
+          DEBUG_MSG (SUBSET, nullptr, "CFF2 subset: local subrs unexpectedly null [%d]", i);
+          return false;
+        }
+        if (unlikely (!subrs->serialize (&c, *acc.privateDicts[i].localSubrs)))
+        {
+          DEBUG_MSG (SUBSET, nullptr, "failed to serialize CFF2 local subrs [%d]", i);
+          return false;
+        }
       }
     }
   }