diff --git a/src/hb-open-file-private.hh b/src/hb-open-file-private.hh
index 47d4e04ff..dda6b9453 100644
--- a/src/hb-open-file-private.hh
+++ b/src/hb-open-file-private.hh
@@ -122,9 +122,9 @@ typedef struct OffsetTable
   USHORT	searchRange;	/* (Maximum power of 2 <= numTables) x 16 */
   USHORT	entrySelector;	/* Log2(maximum power of 2 <= numTables). */
   USHORT	rangeShift;	/* NumTables x 16-searchRange. */
-  TableDirectory tableDir[];	/* TableDirectory entries. numTables items */
+  TableDirectory tableDir[VAR];	/* TableDirectory entries. numTables items */
 } OpenTypeFontFace;
-ASSERT_SIZE (OffsetTable, 12);
+ASSERT_SIZE_VAR (OffsetTable, 12, TableDirectory);
 
 /*
  * TrueType Collections
diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index 4061cfe88..9530c289b 100644
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -50,6 +50,9 @@
 #define CONST_NEXT(T,X)		(*(reinterpret_cast<const T *>(CONST_CHARP(&(X)) + (X).get_size ())))
 #define NEXT(T,X)		(*(reinterpret_cast<T *>(CHARP(&(X)) + (X).get_size ())))
 
+#define CONST_ARRAY_AFTER(T,X)	((reinterpret_cast<const T *>(CONST_CHARP(&(X)) + sizeof (X))))
+#define ARRAY_AFTER(T,X)	((reinterpret_cast<T *>(CHARP(&(X)) + sizeof (X))))
+
 /*
  * Class features
  */
@@ -58,7 +61,7 @@
 /* Null objects */
 
 /* Global nul-content Null pool.  Enlarge as necessary. */
-static const char NullPool[16] = "";
+static const char NullPool[32] = "";
 
 /* Generic template for nul-content sizeof-sized Null objects. */
 template <typename Type>
@@ -505,13 +508,16 @@ struct LongOffsetTo : GenericOffsetTo<LongOffset, Type> {};
 template <typename LenType, typename Type>
 struct GenericArrayOf
 {
+  const Type *const_array(void) const { return CONST_ARRAY_AFTER (Type, len); }
+  Type *array(void) { return ARRAY_AFTER (Type, len); }
+
   inline const Type& operator [] (unsigned int i) const
   {
     if (HB_UNLIKELY (i >= len)) return Null(Type);
-    return array[i];
+    return const_array()[i];
   }
   inline unsigned int get_size () const
-  { return sizeof (len) + len * sizeof (array[0]); }
+  { return sizeof (len) + len * sizeof (Type); }
 
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
@@ -523,7 +529,7 @@ struct GenericArrayOf
     return true;
     unsigned int count = len;
     for (unsigned int i = 0; i < count; i++)
-      if (!SANITIZE (array[i]))
+      if (!SANITIZE (array()[i]))
         return false;
     return true;
   }
@@ -532,7 +538,7 @@ struct GenericArrayOf
     if (!SANITIZE_GET_SIZE()) return false;
     unsigned int count = len;
     for (unsigned int i = 0; i < count; i++)
-      if (!array[i].sanitize (SANITIZE_ARG, base))
+      if (!array()[i].sanitize (SANITIZE_ARG, base))
         return false;
     return true;
   }
@@ -541,7 +547,7 @@ struct GenericArrayOf
     if (!SANITIZE_GET_SIZE()) return false;
     unsigned int count = len;
     for (unsigned int i = 0; i < count; i++)
-      if (!array[i].sanitize (SANITIZE_ARG, base, base2))
+      if (!array()[i].sanitize (SANITIZE_ARG, base, base2))
         return false;
     return true;
   }
@@ -550,13 +556,13 @@ struct GenericArrayOf
     if (!SANITIZE_GET_SIZE()) return false;
     unsigned int count = len;
     for (unsigned int i = 0; i < count; i++)
-      if (!array[i].sanitize (SANITIZE_ARG, base, user_data))
+      if (!array()[i].sanitize (SANITIZE_ARG, base, user_data))
         return false;
     return true;
   }
 
   LenType len;
-  Type array[];
+/*Type array[VAR];*/
 };
 
 /* An array with a USHORT number of elements. */
@@ -586,7 +592,7 @@ struct OffsetListOf : OffsetArrayOf<Type>
   inline const Type& operator [] (unsigned int i) const
   {
     if (HB_UNLIKELY (i >= this->len)) return Null(Type);
-    return this+this->array[i];
+    return this+this->const_array()[i];
   }
 
   inline bool sanitize (SANITIZE_ARG_DEF) {
@@ -605,13 +611,16 @@ struct OffsetListOf : OffsetArrayOf<Type>
 template <typename Type>
 struct HeadlessArrayOf
 {
+  const Type *const_array(void) const { return CONST_ARRAY_AFTER (Type, len); }
+  Type *array(void) { return ARRAY_AFTER (Type, len); }
+
   inline const Type& operator [] (unsigned int i) const
   {
     if (HB_UNLIKELY (i >= len || !i)) return Null(Type);
-    return array[i-1];
+    return const_array()[i-1];
   }
   inline unsigned int get_size () const
-  { return sizeof (len) + (len ? len - 1 : 0) * sizeof (array[0]); }
+  { return sizeof (len) + (len ? len - 1 : 0) * sizeof (Type); }
 
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
@@ -622,14 +631,15 @@ struct HeadlessArrayOf
      * do have a simple sanitize(). */
     return true;
     unsigned int count = len ? len - 1 : 0;
+    Type *a = array();
     for (unsigned int i = 0; i < count; i++)
-      if (!SANITIZE (array[i]))
+      if (!SANITIZE (a[i]))
         return false;
     return true;
   }
 
   USHORT len;
-  Type array[];
+/*Type array[VAR];*/
 };
 
 
diff --git a/src/hb-ot-layout-common-private.hh b/src/hb-ot-layout-common-private.hh
index 0df4a5eb5..3d1bc34a8 100644
--- a/src/hb-ot-layout-common-private.hh
+++ b/src/hb-ot-layout-common-private.hh
@@ -67,14 +67,15 @@ struct RecordArrayOf : ArrayOf<Record<Type> > {
   inline const Tag& get_tag (unsigned int i) const
   {
     if (HB_UNLIKELY (i >= this->len)) return Null(Tag);
-    return this->array[i].tag;
+    return (*this)[i].tag;
   }
   inline bool get_tags (unsigned int *record_count /* IN/OUT */,
 			hb_tag_t     *record_tags /* OUT */) const
   {
+    const Record<Type> *a = this->const_array();
     unsigned int count = MIN (this->len, *record_count);
     for (unsigned int i = 0; i < count; i++)
-      record_tags[i] = this->array[i].tag;
+      record_tags[i] = a[i].tag;
 
     *record_count = this->len;
     return !!this->len;
@@ -83,10 +84,11 @@ struct RecordArrayOf : ArrayOf<Record<Type> > {
   {
     const Tag t = tag;
     // TODO bsearch
+    const Record<Type> *a = this->const_array();
     unsigned int count = this->len;
     for (unsigned int i = 0; i < count; i++)
     {
-      if (t == this->array[i].tag)
+      if (t == a[i].tag)
       {
         if (index) *index = i;
         return true;
@@ -116,14 +118,15 @@ struct IndexArray : ArrayOf<USHORT>
   {
     if (HB_UNLIKELY (i >= this->len))
       return NO_INDEX;
-    return this->array[i];
+    return this->const_array()[i];
   }
   inline bool get_indexes (unsigned int *_count /* IN/OUT */,
 			   unsigned int *_indexes /* OUT */) const
   {
     unsigned int count = MIN (this->len, *_count);
+    const USHORT *a = this->const_array();
     for (unsigned int i = 0; i < count; i++)
-      _indexes[i] = this->array[i];
+      _indexes[i] = a[i];
 
     *_count = this->len;
     return !!this->len;
@@ -283,7 +286,7 @@ struct Lookup
 
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
-    if (!(SANITIZE_SELF () && SANITIZE_THIS (subTable))) return false;
+    if (!(SANITIZE_SELF/*XXXXXXXXXXXXXX*/ () && SANITIZE_THIS (subTable))) return false;
     if (HB_UNLIKELY (lookupFlag & LookupFlag::UseMarkFilteringSet))
     {
       USHORT &markFilteringSet = NEXT (USHORT, subTable);
@@ -296,11 +299,11 @@ struct Lookup
   USHORT	lookupFlag;		/* Lookup qualifiers */
   OffsetArrayOf<LookupSubTable>
 		subTable;		/* Array of SubTables */
-  USHORT	markFilteringSetX[0];	/* Index (base 0) into GDEF mark glyph sets
+  USHORT	markFilteringSetX[VAR];	/* Index (base 0) into GDEF mark glyph sets
 					 * structure. This field is only present if bit
 					 * UseMarkFilteringSet of lookup flags is set. */
 };
-ASSERT_SIZE (Lookup, 6);
+ASSERT_SIZE_VAR (Lookup, 6, USHORT);
 
 typedef OffsetListOf<Lookup> LookupList;
 ASSERT_SIZE (LookupList, 2);
@@ -425,11 +428,10 @@ struct Coverage
   private:
   union {
   USHORT		format;		/* Format identifier */
-  CoverageFormat1	format1[];
-  CoverageFormat2	format2[];
+  CoverageFormat1	format1[VAR];
+  CoverageFormat2	format2[VAR];
   } u;
 };
-ASSERT_SIZE (Coverage, 2);
 
 
 /*
@@ -541,11 +543,10 @@ struct ClassDef
   private:
   union {
   USHORT		format;		/* Format identifier */
-  ClassDefFormat1	format1[];
-  ClassDefFormat2	format2[];
+  ClassDefFormat1	format1[VAR];
+  ClassDefFormat2	format2[VAR];
   } u;
 };
-ASSERT_SIZE (ClassDef, 2);
 
 
 /*
@@ -595,9 +596,9 @@ struct Device
   USHORT	startSize;	/* Smallest size to correct--in ppem */
   USHORT	endSize;	/* Largest size to correct--in ppem */
   USHORT	deltaFormat;	/* Format of DeltaValue array data: 1, 2, or 3 */
-  USHORT	deltaValue[];	/* Array of compressed data */
+  USHORT	deltaValue[VAR];	/* Array of compressed data */
 };
-ASSERT_SIZE (Device, 6);
+ASSERT_SIZE_VAR (Device, 6, USHORT);
 
 
 #endif /* HB_OT_LAYOUT_COMMON_PRIVATE_HH */
diff --git a/src/hb-ot-layout-gdef-private.hh b/src/hb-ot-layout-gdef-private.hh
index 1eb96c0d0..69f90fec1 100644
--- a/src/hb-ot-layout-gdef-private.hh
+++ b/src/hb-ot-layout-gdef-private.hh
@@ -177,12 +177,11 @@ struct CaretValue
   private:
   union {
   USHORT		format;		/* Format identifier */
-  CaretValueFormat1	format1[];
-  CaretValueFormat2	format2[];
-  CaretValueFormat3	format3[];
+  CaretValueFormat1	format1[VAR];
+  CaretValueFormat2	format2[VAR];
+  CaretValueFormat3	format3[VAR];
   } u;
 };
-ASSERT_SIZE (CaretValue, 2);
 
 struct LigGlyph
 {
@@ -286,10 +285,9 @@ struct MarkGlyphSets
   private:
   union {
   USHORT		format;		/* Format identifier */
-  MarkGlyphSetsFormat1	format1[];
+  MarkGlyphSetsFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (MarkGlyphSets, 2);
 
 
 /*
@@ -364,12 +362,12 @@ struct GDEF
 					 * mark attachment type--from beginning
 					 * of GDEF header (may be Null) */
   OffsetTo<MarkGlyphSets>
-		markGlyphSetsDef[0];	/* Offset to the table of mark set
+		markGlyphSetsDef[VAR];	/* Offset to the table of mark set
 					 * definitions--from beginning of GDEF
 					 * header (may be NULL).  Introduced
 					 * in version 00010002. */
 };
-ASSERT_SIZE (GDEF, 12);
+ASSERT_SIZE_VAR (GDEF, 12, OffsetTo<MarkGlyphSets>);
 
 
 #endif /* HB_OT_LAYOUT_GDEF_PRIVATE_HH */
diff --git a/src/hb-ot-layout-gpos-private.hh b/src/hb-ot-layout-gpos-private.hh
index 609ebe783..5d9fd48e0 100644
--- a/src/hb-ot-layout-gpos-private.hh
+++ b/src/hb-ot-layout-gpos-private.hh
@@ -35,8 +35,8 @@
 
 typedef SHORT Value;
 
-typedef Value ValueRecord[0];
-ASSERT_SIZE (ValueRecord, 0);
+typedef Value ValueRecord[VAR];
+ASSERT_SIZE_VAR (Value, 0, ValueRecord);
 
 struct ValueFormat : USHORT
 {
@@ -259,12 +259,11 @@ struct Anchor
   private:
   union {
   USHORT		format;		/* Format identifier */
-  AnchorFormat1		format1[];
-  AnchorFormat2		format2[];
-  AnchorFormat3		format3[];
+  AnchorFormat1		format1[VAR];
+  AnchorFormat2		format2[VAR];
+  AnchorFormat3		format3[VAR];
   } u;
 };
-ASSERT_SIZE (Anchor, 2);
 
 
 struct AnchorMatrix
@@ -287,10 +286,10 @@ struct AnchorMatrix
   USHORT	rows;			/* Number of rows */
   private:
   OffsetTo<Anchor>
-		matrix[];		/* Matrix of offsets to Anchor tables--
+		matrix[VAR];		/* Matrix of offsets to Anchor tables--
 					 * from beginning of AnchorMatrix table */
 };
-ASSERT_SIZE (AnchorMatrix, 2);
+ASSERT_SIZE_VAR (AnchorMatrix, 2, OffsetTo<Anchor>);
 
 
 struct MarkRecord
@@ -389,7 +388,7 @@ struct SinglePosFormat1
 					 * value(s)--applied to all glyphs in
 					 * the Coverage table */
 };
-ASSERT_SIZE (SinglePosFormat1, 6);
+ASSERT_SIZE_VAR (SinglePosFormat1, 6, ValueRecord);
 
 struct SinglePosFormat2
 {
@@ -431,7 +430,7 @@ struct SinglePosFormat2
   ValueRecord	values;			/* Array of ValueRecords--positioning
 					 * values applied to glyphs */
 };
-ASSERT_SIZE (SinglePosFormat2, 8);
+ASSERT_SIZE_VAR (SinglePosFormat2, 8, ValueRecord);
 
 struct SinglePos
 {
@@ -461,11 +460,10 @@ struct SinglePos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  SinglePosFormat1	format1[];
-  SinglePosFormat2	format2[];
+  SinglePosFormat1	format1[VAR];
+  SinglePosFormat2	format2[VAR];
   } u;
 };
-ASSERT_SIZE (SinglePos, 2);
 
 
 struct PairValueRecord
@@ -479,7 +477,7 @@ struct PairValueRecord
   ValueRecord	values;			/* Positioning data for the first glyph
 					 * followed by for second glyph */
 };
-ASSERT_SIZE (PairValueRecord, 2);
+ASSERT_SIZE_VAR (PairValueRecord, 2, ValueRecord);
 
 struct PairSet
 {
@@ -495,10 +493,10 @@ struct PairSet
   private:
   USHORT	len;			/* Number of PairValueRecords */
   PairValueRecord
-		array[];		/* Array of PairValueRecords--ordered
+		array[VAR];		/* Array of PairValueRecords--ordered
 					 * by GlyphID of the second glyph */
 };
-ASSERT_SIZE (PairSet, 2);
+ASSERT_SIZE_VAR (PairSet, 2, PairValueRecord);
 
 struct PairPosFormat1
 {
@@ -654,7 +652,7 @@ struct PairPosFormat2
 					 * class1-major, class2-minor,
 					 * Each entry has value1 and value2 */
 };
-ASSERT_SIZE (PairPosFormat2, 16);
+ASSERT_SIZE_VAR (PairPosFormat2, 16, ValueRecord);
 
 struct PairPos
 {
@@ -684,11 +682,10 @@ struct PairPos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  PairPosFormat1	format1[];
-  PairPosFormat2	format2[];
+  PairPosFormat1	format1[VAR];
+  PairPosFormat2	format2[VAR];
   } u;
 };
-ASSERT_SIZE (PairPos, 2);
 
 
 struct EntryExitRecord
@@ -931,17 +928,15 @@ struct CursivePos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  CursivePosFormat1	format1[];
+  CursivePosFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (CursivePos, 2);
 
 
 typedef AnchorMatrix BaseArray;		/* base-major--
 					 * in order of BaseCoverage Index--,
 					 * mark-minor--
 					 * ordered by class--zero-based. */
-ASSERT_SIZE (BaseArray, 2);
 
 struct MarkBasePosFormat1
 {
@@ -1027,23 +1022,20 @@ struct MarkBasePos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  MarkBasePosFormat1	format1[];
+  MarkBasePosFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (MarkBasePos, 2);
 
 
 typedef AnchorMatrix LigatureAttach;	/* component-major--
 					 * in order of writing direction--,
 					 * mark-minor--
 					 * ordered by class--zero-based. */
-ASSERT_SIZE (LigatureAttach, 2);
 
 typedef OffsetListOf<LigatureAttach> LigatureArray;
 					/* Array of LigatureAttach
 					 * tables ordered by
 					 * LigatureCoverage Index */
-ASSERT_SIZE (LigatureArray, 2);
 
 struct MarkLigPosFormat1
 {
@@ -1152,17 +1144,15 @@ struct MarkLigPos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  MarkLigPosFormat1	format1[];
+  MarkLigPosFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (MarkLigPos, 2);
 
 
 typedef AnchorMatrix Mark2Array;	/* mark2-major--
 					 * in order of Mark2Coverage Index--,
 					 * mark1-minor--
 					 * ordered by class--zero-based. */
-ASSERT_SIZE (Mark2Array, 2);
 
 struct MarkMarkPosFormat1
 {
@@ -1253,10 +1243,9 @@ struct MarkMarkPos
   private:
   union {
   USHORT		format;		/* Format identifier */
-  MarkMarkPosFormat1	format1[];
+  MarkMarkPosFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (MarkMarkPos, 2);
 
 
 static inline bool position_lookup (APPLY_ARG_DEF, unsigned int lookup_index);
@@ -1272,7 +1261,6 @@ struct ContextPos : Context
     return Context::apply (APPLY_ARG, position_lookup);
   }
 };
-ASSERT_SIZE (ContextPos, 2);
 
 struct ChainContextPos : ChainContext
 {
@@ -1285,7 +1273,6 @@ struct ChainContextPos : ChainContext
     return ChainContext::apply (APPLY_ARG, position_lookup);
   }
 };
-ASSERT_SIZE (ChainContextPos, 2);
 
 
 struct ExtensionPos : Extension
@@ -1300,7 +1287,6 @@ struct ExtensionPos : Extension
 
   inline bool sanitize (SANITIZE_ARG_DEF);
 };
-ASSERT_SIZE (ExtensionPos, 2);
 
 
 
@@ -1362,18 +1348,17 @@ struct PosLookupSubTable
   private:
   union {
   USHORT		format;
-  SinglePos		single[];
-  PairPos		pair[];
-  CursivePos		cursive[];
-  MarkBasePos		markBase[];
-  MarkLigPos		markLig[];
-  MarkMarkPos		markMark[];
-  ContextPos		context[];
-  ChainContextPos	chainContext[];
-  ExtensionPos		extension[];
+  SinglePos		single[VAR];
+  PairPos		pair[VAR];
+  CursivePos		cursive[VAR];
+  MarkBasePos		markBase[VAR];
+  MarkLigPos		markLig[VAR];
+  MarkMarkPos		markMark[VAR];
+  ContextPos		context[VAR];
+  ChainContextPos	chainContext[VAR];
+  ExtensionPos		extension[VAR];
   } u;
 };
-ASSERT_SIZE (PosLookupSubTable, 2);
 
 
 struct PosLookup : Lookup
@@ -1462,7 +1447,6 @@ struct PosLookup : Lookup
     return SANITIZE_THIS (list);
   }
 };
-ASSERT_SIZE (PosLookup, 6);
 
 typedef OffsetListOf<PosLookup> PosLookupList;
 ASSERT_SIZE (PosLookupList, 2);
diff --git a/src/hb-ot-layout-gsub-private.hh b/src/hb-ot-layout-gsub-private.hh
index bd29cf74c..dde1cf5ab 100644
--- a/src/hb-ot-layout-gsub-private.hh
+++ b/src/hb-ot-layout-gsub-private.hh
@@ -141,11 +141,10 @@ struct SingleSubst
   private:
   union {
   USHORT		format;		/* Format identifier */
-  SingleSubstFormat1	format1[];
-  SingleSubstFormat2	format2[];
+  SingleSubstFormat1	format1[VAR];
+  SingleSubstFormat2	format2[VAR];
   } u;
 };
-ASSERT_SIZE (SingleSubst, 2);
 
 
 struct Sequence
@@ -160,7 +159,7 @@ struct Sequence
       return false;
 
     _hb_buffer_add_output_glyphs (buffer, 1,
-				  substitute.len, (const uint16_t *) substitute.array,
+				  substitute.len, (const uint16_t *) substitute.const_array(),
 				  0xFFFF, 0xFFFF);
 
     /* This is a guess only ... */
@@ -249,10 +248,9 @@ struct MultipleSubst
   private:
   union {
   USHORT		format;		/* Format identifier */
-  MultipleSubstFormat1	format1[];
+  MultipleSubstFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (MultipleSubst, 2);
 
 
 typedef ArrayOf<GlyphID> AlternateSet;	/* Array of alternate GlyphIDs--in
@@ -345,10 +343,9 @@ struct AlternateSubst
   private:
   union {
   USHORT		format;		/* Format identifier */
-  AlternateSubstFormat1	format1[];
+  AlternateSubstFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (AlternateSubst, 2);
 
 
 struct Ligature
@@ -531,10 +528,9 @@ struct LigatureSubst
   private:
   union {
   USHORT		format;		/* Format identifier */
-  LigatureSubstFormat1	format1[];
+  LigatureSubstFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (LigatureSubst, 2);
 
 
 
@@ -551,7 +547,6 @@ struct ContextSubst : Context
     return Context::apply (APPLY_ARG, substitute_lookup);
   }
 };
-ASSERT_SIZE (ContextSubst, 2);
 
 struct ChainContextSubst : ChainContext
 {
@@ -564,7 +559,6 @@ struct ChainContextSubst : ChainContext
     return ChainContext::apply (APPLY_ARG, substitute_lookup);
   }
 };
-ASSERT_SIZE (ChainContextSubst, 2);
 
 
 struct ExtensionSubst : Extension
@@ -579,7 +573,6 @@ struct ExtensionSubst : Extension
 
   inline bool sanitize (SANITIZE_ARG_DEF);
 };
-ASSERT_SIZE (ExtensionSubst, 2);
 
 
 struct ReverseChainSingleSubstFormat1
@@ -601,10 +594,10 @@ struct ReverseChainSingleSubstFormat1
     const ArrayOf<GlyphID> &substitute = CONST_NEXT (ArrayOf<GlyphID>, lookahead);
 
     if (match_backtrack (APPLY_ARG,
-			 backtrack.len, (USHORT *) backtrack.array,
+			 backtrack.len, (USHORT *) backtrack.const_array(),
 			 match_coverage, DECONST_CHARP(this)) &&
         match_lookahead (APPLY_ARG,
-			 lookahead.len, (USHORT *) lookahead.array,
+			 lookahead.len, (USHORT *) lookahead.const_array(),
 			 match_coverage, DECONST_CHARP(this),
 			 1))
     {
@@ -672,10 +665,9 @@ struct ReverseChainSingleSubst
   private:
   union {
   USHORT				format;		/* Format identifier */
-  ReverseChainSingleSubstFormat1	format1[];
+  ReverseChainSingleSubstFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (ReverseChainSingleSubst, 2);
 
 
 
@@ -733,17 +725,16 @@ struct SubstLookupSubTable
   private:
   union {
   USHORT			format;
-  SingleSubst			single[];
-  MultipleSubst			multiple[];
-  AlternateSubst		alternate[];
-  LigatureSubst			ligature[];
-  ContextSubst			context[];
-  ChainContextSubst		chainContext[];
-  ExtensionSubst		extension[];
-  ReverseChainSingleSubst	reverseChainContextSingle[];
+  SingleSubst			single[VAR];
+  MultipleSubst			multiple[VAR];
+  AlternateSubst		alternate[VAR];
+  LigatureSubst			ligature[VAR];
+  ContextSubst			context[VAR];
+  ChainContextSubst		chainContext[VAR];
+  ExtensionSubst		extension[VAR];
+  ReverseChainSingleSubst	reverseChainContextSingle[VAR];
   } u;
 };
-ASSERT_SIZE (SubstLookupSubTable, 2);
 
 
 struct SubstLookup : Lookup
@@ -846,7 +837,6 @@ struct SubstLookup : Lookup
     return SANITIZE_THIS (list);
   }
 };
-ASSERT_SIZE (SubstLookup, 6);
 
 typedef OffsetListOf<SubstLookup> SubstLookupList;
 ASSERT_SIZE (SubstLookupList, 2);
diff --git a/src/hb-ot-layout-gsubgpos-private.hh b/src/hb-ot-layout-gsubgpos-private.hh
index 8b9b1cd43..91703da31 100644
--- a/src/hb-ot-layout-gsubgpos-private.hh
+++ b/src/hb-ot-layout-gsubgpos-private.hh
@@ -307,7 +307,7 @@ struct Rule
   public:
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
-    if (!SANITIZE_SELF ()) return false;
+    if (!(SANITIZE (inputCount) && SANITIZE (lookupCount))) return false;
     return SANITIZE_MEM (input,
 			 sizeof (input[0]) * inputCount +
 			 sizeof (lookupRecordX[0]) * lookupCount);
@@ -318,12 +318,12 @@ struct Rule
 					 * glyph sequence--includes the  first
 					 * glyph */
   USHORT	lookupCount;		/* Number of LookupRecords */
-  USHORT	input[];		/* Array of match inputs--start with
+  USHORT	input[VAR];		/* Array of match inputs--start with
 					 * second glyph */
-  LookupRecord	lookupRecordX[];	/* Array of LookupRecords--in
+  LookupRecord	lookupRecordX[VAR];	/* Array of LookupRecords--in
 					 * design order */
 };
-ASSERT_SIZE (Rule, 4);
+ASSERT_SIZE_VAR2 (Rule, 4, USHORT, LookupRecord);
 
 struct RuleSet
 {
@@ -473,12 +473,12 @@ struct ContextFormat3
 					 * sequence */
   USHORT	lookupCount;		/* Number of LookupRecords */
   OffsetTo<Coverage>
-		coverage[];		/* Array of offsets to Coverage
+		coverage[VAR];		/* Array of offsets to Coverage
 					 * table in glyph sequence order */
-  LookupRecord	lookupRecordX[];	/* Array of LookupRecords--in
+  LookupRecord	lookupRecordX[VAR];	/* Array of LookupRecords--in
 					 * design order */
 };
-ASSERT_SIZE (ContextFormat3, 6);
+ASSERT_SIZE_VAR2 (ContextFormat3, 6, OffsetTo<Coverage>, LookupRecord);
 
 struct Context
 {
@@ -508,12 +508,11 @@ struct Context
   private:
   union {
   USHORT		format;		/* Format identifier */
-  ContextFormat1	format1[];
-  ContextFormat2	format2[];
-  ContextFormat3	format3[];
+  ContextFormat1	format1[VAR];
+  ContextFormat2	format2[VAR];
+  ContextFormat3	format3[VAR];
   } u;
 };
-ASSERT_SIZE (Context, 2);
 
 
 /* Chaining Contextual lookups */
@@ -572,10 +571,10 @@ struct ChainRule
     const ArrayOf<USHORT> &lookahead = CONST_NEXT (ArrayOf<USHORT>, input);
     const ArrayOf<LookupRecord> &lookup = CONST_NEXT (ArrayOf<LookupRecord>, lookahead);
     return chain_context_lookup (APPLY_ARG,
-				 backtrack.len, backtrack.array,
-				 input.len, input.array,
-				 lookahead.len, lookahead.array,
-				 lookup.len, lookup.array,
+				 backtrack.len, backtrack.const_array(),
+				 input.len, input.const_array(),
+				 lookahead.len, lookahead.const_array(),
+				 lookup.len, lookup.const_array(),
 				 lookup_context);
     return false;
   }
@@ -754,10 +753,10 @@ struct ChainContextFormat3
       {DECONST_CHARP(this), DECONST_CHARP(this), DECONST_CHARP(this)}
     };
     return chain_context_lookup (APPLY_ARG,
-				 backtrack.len, (USHORT *) backtrack.array,
-				 input.len, (USHORT *) input.array + 1,
-				 lookahead.len, (USHORT *) lookahead.array,
-				 lookup.len, lookup.array,
+				 backtrack.len, (const USHORT *) backtrack.const_array(),
+				 input.len, (const USHORT *) input.const_array() + 1,
+				 lookahead.len, (const USHORT *) lookahead.const_array(),
+				 lookup.len, lookup.const_array(),
 				 lookup_context);
     return false;
   }
@@ -821,12 +820,11 @@ struct ChainContext
   private:
   union {
   USHORT		format;	/* Format identifier */
-  ChainContextFormat1	format1[];
-  ChainContextFormat2	format2[];
-  ChainContextFormat3	format3[];
+  ChainContextFormat1	format1[VAR];
+  ChainContextFormat2	format2[VAR];
+  ChainContextFormat3	format3[VAR];
   } u;
 };
-ASSERT_SIZE (ChainContext, 2);
 
 
 struct ExtensionFormat1
@@ -889,10 +887,9 @@ struct Extension
   private:
   union {
   USHORT		format;		/* Format identifier */
-  ExtensionFormat1	format1[];
+  ExtensionFormat1	format1[VAR];
   } u;
 };
-ASSERT_SIZE (Extension, 2);
 
 
 /*
diff --git a/src/hb-private.h b/src/hb-private.h
index f040ae520..fcebe5638 100644
--- a/src/hb-private.h
+++ b/src/hb-private.h
@@ -139,6 +139,11 @@ typedef int hb_mutex_t;
 
 #define ASSERT_SIZE(_type, _size) ASSERT_STATIC (sizeof (_type) == (_size))
 
+#define VAR 1 /* Size signifying variable-sized array */
+#define ASSERT_SIZE_VAR(_type, _size, _var_type) \
+	ASSERT_STATIC (sizeof (_type) == (_size) + VAR * sizeof (_var_type))
+#define ASSERT_SIZE_VAR2(_type, _size, _var_type1, _var_type2) \
+	ASSERT_STATIC (sizeof (_type) == (_size) + VAR * sizeof (_var_type1) + VAR * sizeof (_var_type2))
 
 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 #define _HB_BOOLEAN_EXPR(expr)                   \