diff --git a/php/ext/google/protobuf/php-upb.c b/php/ext/google/protobuf/php-upb.c
index 4f9b9e7..454fd69 100644
--- a/php/ext/google/protobuf/php-upb.c
+++ b/php/ext/google/protobuf/php-upb.c
@@ -6211,6 +6211,7 @@
 }
 
 
+#include <stdint.h>
 #include <string.h>
 
 
@@ -6231,7 +6232,7 @@
 upb_MessageValue upb_Array_Get(const upb_Array* arr, size_t i) {
   upb_MessageValue ret;
   const char* data = _upb_array_constptr(arr);
-  int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   UPB_ASSERT(i < arr->size);
   memcpy(&ret, data + (i << lg2), 1 << lg2);
   return ret;
@@ -6239,7 +6240,7 @@
 
 void upb_Array_Set(upb_Array* arr, size_t i, upb_MessageValue val) {
   char* data = _upb_array_ptr(arr);
-  int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   UPB_ASSERT(i < arr->size);
   memcpy(data + (i << lg2), &val, 1 << lg2);
 }
@@ -6255,7 +6256,7 @@
 
 void upb_Array_Move(upb_Array* arr, size_t dst_idx, size_t src_idx,
                     size_t count) {
-  const int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   char* data = _upb_array_ptr(arr);
   memmove(&data[dst_idx << lg2], &data[src_idx << lg2], count << lg2);
 }
@@ -6292,7 +6293,7 @@
   }
   const size_t newsize = arr->size;
   if (newsize > oldsize) {
-    const int lg2 = arr->data & 7;
+    const int lg2 = _upb_Array_ElemSizeLg2(arr);
     char* data = _upb_array_ptr(arr);
     memset(data + (oldsize << lg2), 0, (newsize - oldsize) << lg2);
   }
@@ -6303,19 +6304,18 @@
 
 bool _upb_array_realloc(upb_Array* arr, size_t min_capacity, upb_Arena* arena) {
   size_t new_capacity = UPB_MAX(arr->capacity, 4);
-  int elem_size_lg2 = arr->data & 7;
-  size_t old_bytes = arr->capacity << elem_size_lg2;
-  size_t new_bytes;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
+  size_t old_bytes = arr->capacity << lg2;
   void* ptr = _upb_array_ptr(arr);
 
   // Log2 ceiling of size.
   while (new_capacity < min_capacity) new_capacity *= 2;
 
-  new_bytes = new_capacity << elem_size_lg2;
+  const size_t new_bytes = new_capacity << lg2;
   ptr = upb_Arena_Realloc(arena, ptr, old_bytes, new_bytes);
   if (!ptr) return false;
 
-  arr->data = _upb_tag_arrptr(ptr, elem_size_lg2);
+  _upb_Array_SetTaggedPtr(arr, ptr, lg2);
   arr->capacity = new_capacity;
   return true;
 }
@@ -14029,17 +14029,17 @@
 static void* fastdecode_resizearr(upb_Decoder* d, void* dst,
                                   fastdecode_arr* farr, int valbytes) {
   if (UPB_UNLIKELY(dst == farr->end)) {
-    size_t old_size = farr->arr->capacity;
-    size_t old_bytes = old_size * valbytes;
-    size_t new_size = old_size * 2;
-    size_t new_bytes = new_size * valbytes;
+    size_t old_capacity = farr->arr->capacity;
+    size_t old_bytes = old_capacity * valbytes;
+    size_t new_capacity = old_capacity * 2;
+    size_t new_bytes = new_capacity * valbytes;
     char* old_ptr = _upb_array_ptr(farr->arr);
     char* new_ptr = upb_Arena_Realloc(&d->arena, old_ptr, old_bytes, new_bytes);
     uint8_t elem_size_lg2 = __builtin_ctz(valbytes);
-    farr->arr->capacity = new_size;
-    farr->arr->data = _upb_array_tagptr(new_ptr, elem_size_lg2);
-    dst = (void*)(new_ptr + (old_size * valbytes));
-    farr->end = (void*)(new_ptr + (new_size * valbytes));
+    _upb_Array_SetTaggedPtr(farr->arr, new_ptr, elem_size_lg2);
+    farr->arr->capacity = new_capacity;
+    dst = (void*)(new_ptr + (old_capacity * valbytes));
+    farr->end = (void*)(new_ptr + (new_capacity * valbytes));
   }
   return dst;
 }
diff --git a/php/ext/google/protobuf/php-upb.h b/php/ext/google/protobuf/php-upb.h
index ba43d2f..f80121d 100644
--- a/php/ext/google/protobuf/php-upb.h
+++ b/php/ext/google/protobuf/php-upb.h
@@ -2572,6 +2572,10 @@
 
 // Must be last.
 
+#define _UPB_ARRAY_MASK_IMM 0x4  // Frozen/immutable bit.
+#define _UPB_ARRAY_MASK_LG2 0x3  // Encoded elem size.
+#define _UPB_ARRAY_MASK_ALL (_UPB_ARRAY_MASK_IMM | _UPB_ARRAY_MASK_LG2)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -2579,46 +2583,52 @@
 // LINT.IfChange(struct_definition)
 // Our internal representation for repeated fields.
 struct upb_Array {
-  uintptr_t data;  /* Tagged ptr: low 3 bits of ptr are lg2(elem size). */
-  size_t size;     /* The number of elements in the array. */
-  size_t capacity; /* Allocated storage. Measured in elements. */
+  // This is a tagged pointer. Bits #0 and #1 encode the elem size as follows:
+  //   0 maps to elem size 1
+  //   1 maps to elem size 4
+  //   2 maps to elem size 8
+  //   3 maps to elem size 16
+  //
+  // Bit #2 contains the frozen/immutable flag (currently unimplemented).
+  uintptr_t data;
+
+  size_t size;      // The number of elements in the array.
+  size_t capacity;  // Allocated storage. Measured in elements.
 };
 // LINT.ThenChange(GoogleInternalName1)
 
-UPB_INLINE size_t _upb_Array_ElementSizeLg2(const upb_Array* arr) {
-  size_t ret = arr->data & 7;
-  UPB_ASSERT(ret <= 4);
-  return ret;
+UPB_INLINE void _upb_Array_SetTaggedPtr(upb_Array* arr, void* data,
+                                        size_t lg2) {
+  UPB_ASSERT(lg2 != 1);
+  UPB_ASSERT(lg2 <= 4);
+  const size_t bits = lg2 - (lg2 != 0);
+  arr->data = (uintptr_t)data | bits;
+}
+
+UPB_INLINE size_t _upb_Array_ElemSizeLg2(const upb_Array* arr) {
+  const size_t bits = arr->data & _UPB_ARRAY_MASK_LG2;
+  const size_t lg2 = bits + (bits != 0);
+  return lg2;
 }
 
 UPB_INLINE const void* _upb_array_constptr(const upb_Array* arr) {
-  _upb_Array_ElementSizeLg2(arr);  // Check assertion.
-  return (void*)(arr->data & ~(uintptr_t)7);
-}
-
-UPB_INLINE uintptr_t _upb_array_tagptr(void* ptr, int elem_size_lg2) {
-  UPB_ASSERT(elem_size_lg2 <= 4);
-  return (uintptr_t)ptr | elem_size_lg2;
+  _upb_Array_ElemSizeLg2(arr);  // Check assertions.
+  return (void*)(arr->data & ~(uintptr_t)_UPB_ARRAY_MASK_ALL);
 }
 
 UPB_INLINE void* _upb_array_ptr(upb_Array* arr) {
   return (void*)_upb_array_constptr(arr);
 }
 
-UPB_INLINE uintptr_t _upb_tag_arrptr(void* ptr, int elem_size_lg2) {
-  UPB_ASSERT(elem_size_lg2 <= 4);
-  UPB_ASSERT(((uintptr_t)ptr & 7) == 0);
-  return (uintptr_t)ptr | (unsigned)elem_size_lg2;
-}
-
 UPB_INLINE upb_Array* _upb_Array_New(upb_Arena* a, size_t init_capacity,
                                      int elem_size_lg2) {
+  UPB_ASSERT(elem_size_lg2 != 1);
   UPB_ASSERT(elem_size_lg2 <= 4);
   const size_t arr_size = UPB_ALIGN_UP(sizeof(upb_Array), UPB_MALLOC_ALIGN);
   const size_t bytes = arr_size + (init_capacity << elem_size_lg2);
   upb_Array* arr = (upb_Array*)upb_Arena_Malloc(a, bytes);
   if (!arr) return NULL;
-  arr->data = _upb_tag_arrptr(UPB_PTR_AT(arr, arr_size, void), elem_size_lg2);
+  _upb_Array_SetTaggedPtr(arr, UPB_PTR_AT(arr, arr_size, void), elem_size_lg2);
   arr->size = 0;
   arr->capacity = init_capacity;
   return arr;
@@ -2648,7 +2658,7 @@
 UPB_INLINE void _upb_Array_Set(upb_Array* arr, size_t i, const void* data,
                                size_t elem_size) {
   UPB_ASSERT(i < arr->size);
-  UPB_ASSERT(elem_size == 1U << _upb_Array_ElementSizeLg2(arr));
+  UPB_ASSERT(elem_size == 1U << _upb_Array_ElemSizeLg2(arr));
   char* arr_data = (char*)_upb_array_ptr(arr);
   memcpy(arr_data + (i * elem_size), data, elem_size);
 }
@@ -2661,6 +2671,10 @@
 } /* extern "C" */
 #endif
 
+#undef _UPB_ARRAY_MASK_IMM
+#undef _UPB_ARRAY_MASK_LG2
+#undef _UPB_ARRAY_MASK_ALL
+
 
 #endif /* UPB_MESSAGE_INTERNAL_ARRAY_H_ */
 
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.c b/ruby/ext/google/protobuf_c/ruby-upb.c
index 13eaf31..7059996 100644
--- a/ruby/ext/google/protobuf_c/ruby-upb.c
+++ b/ruby/ext/google/protobuf_c/ruby-upb.c
@@ -5726,6 +5726,7 @@
 }
 
 
+#include <stdint.h>
 #include <string.h>
 
 
@@ -5746,7 +5747,7 @@
 upb_MessageValue upb_Array_Get(const upb_Array* arr, size_t i) {
   upb_MessageValue ret;
   const char* data = _upb_array_constptr(arr);
-  int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   UPB_ASSERT(i < arr->size);
   memcpy(&ret, data + (i << lg2), 1 << lg2);
   return ret;
@@ -5754,7 +5755,7 @@
 
 void upb_Array_Set(upb_Array* arr, size_t i, upb_MessageValue val) {
   char* data = _upb_array_ptr(arr);
-  int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   UPB_ASSERT(i < arr->size);
   memcpy(data + (i << lg2), &val, 1 << lg2);
 }
@@ -5770,7 +5771,7 @@
 
 void upb_Array_Move(upb_Array* arr, size_t dst_idx, size_t src_idx,
                     size_t count) {
-  const int lg2 = arr->data & 7;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
   char* data = _upb_array_ptr(arr);
   memmove(&data[dst_idx << lg2], &data[src_idx << lg2], count << lg2);
 }
@@ -5807,7 +5808,7 @@
   }
   const size_t newsize = arr->size;
   if (newsize > oldsize) {
-    const int lg2 = arr->data & 7;
+    const int lg2 = _upb_Array_ElemSizeLg2(arr);
     char* data = _upb_array_ptr(arr);
     memset(data + (oldsize << lg2), 0, (newsize - oldsize) << lg2);
   }
@@ -5818,19 +5819,18 @@
 
 bool _upb_array_realloc(upb_Array* arr, size_t min_capacity, upb_Arena* arena) {
   size_t new_capacity = UPB_MAX(arr->capacity, 4);
-  int elem_size_lg2 = arr->data & 7;
-  size_t old_bytes = arr->capacity << elem_size_lg2;
-  size_t new_bytes;
+  const int lg2 = _upb_Array_ElemSizeLg2(arr);
+  size_t old_bytes = arr->capacity << lg2;
   void* ptr = _upb_array_ptr(arr);
 
   // Log2 ceiling of size.
   while (new_capacity < min_capacity) new_capacity *= 2;
 
-  new_bytes = new_capacity << elem_size_lg2;
+  const size_t new_bytes = new_capacity << lg2;
   ptr = upb_Arena_Realloc(arena, ptr, old_bytes, new_bytes);
   if (!ptr) return false;
 
-  arr->data = _upb_tag_arrptr(ptr, elem_size_lg2);
+  _upb_Array_SetTaggedPtr(arr, ptr, lg2);
   arr->capacity = new_capacity;
   return true;
 }
@@ -13544,17 +13544,17 @@
 static void* fastdecode_resizearr(upb_Decoder* d, void* dst,
                                   fastdecode_arr* farr, int valbytes) {
   if (UPB_UNLIKELY(dst == farr->end)) {
-    size_t old_size = farr->arr->capacity;
-    size_t old_bytes = old_size * valbytes;
-    size_t new_size = old_size * 2;
-    size_t new_bytes = new_size * valbytes;
+    size_t old_capacity = farr->arr->capacity;
+    size_t old_bytes = old_capacity * valbytes;
+    size_t new_capacity = old_capacity * 2;
+    size_t new_bytes = new_capacity * valbytes;
     char* old_ptr = _upb_array_ptr(farr->arr);
     char* new_ptr = upb_Arena_Realloc(&d->arena, old_ptr, old_bytes, new_bytes);
     uint8_t elem_size_lg2 = __builtin_ctz(valbytes);
-    farr->arr->capacity = new_size;
-    farr->arr->data = _upb_array_tagptr(new_ptr, elem_size_lg2);
-    dst = (void*)(new_ptr + (old_size * valbytes));
-    farr->end = (void*)(new_ptr + (new_size * valbytes));
+    _upb_Array_SetTaggedPtr(farr->arr, new_ptr, elem_size_lg2);
+    farr->arr->capacity = new_capacity;
+    dst = (void*)(new_ptr + (old_capacity * valbytes));
+    farr->end = (void*)(new_ptr + (new_capacity * valbytes));
   }
   return dst;
 }
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.h b/ruby/ext/google/protobuf_c/ruby-upb.h
index 7958339..33e0e3c 100755
--- a/ruby/ext/google/protobuf_c/ruby-upb.h
+++ b/ruby/ext/google/protobuf_c/ruby-upb.h
@@ -2574,6 +2574,10 @@
 
 // Must be last.
 
+#define _UPB_ARRAY_MASK_IMM 0x4  // Frozen/immutable bit.
+#define _UPB_ARRAY_MASK_LG2 0x3  // Encoded elem size.
+#define _UPB_ARRAY_MASK_ALL (_UPB_ARRAY_MASK_IMM | _UPB_ARRAY_MASK_LG2)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -2581,46 +2585,52 @@
 // LINT.IfChange(struct_definition)
 // Our internal representation for repeated fields.
 struct upb_Array {
-  uintptr_t data;  /* Tagged ptr: low 3 bits of ptr are lg2(elem size). */
-  size_t size;     /* The number of elements in the array. */
-  size_t capacity; /* Allocated storage. Measured in elements. */
+  // This is a tagged pointer. Bits #0 and #1 encode the elem size as follows:
+  //   0 maps to elem size 1
+  //   1 maps to elem size 4
+  //   2 maps to elem size 8
+  //   3 maps to elem size 16
+  //
+  // Bit #2 contains the frozen/immutable flag (currently unimplemented).
+  uintptr_t data;
+
+  size_t size;      // The number of elements in the array.
+  size_t capacity;  // Allocated storage. Measured in elements.
 };
 // LINT.ThenChange(GoogleInternalName1)
 
-UPB_INLINE size_t _upb_Array_ElementSizeLg2(const upb_Array* arr) {
-  size_t ret = arr->data & 7;
-  UPB_ASSERT(ret <= 4);
-  return ret;
+UPB_INLINE void _upb_Array_SetTaggedPtr(upb_Array* arr, void* data,
+                                        size_t lg2) {
+  UPB_ASSERT(lg2 != 1);
+  UPB_ASSERT(lg2 <= 4);
+  const size_t bits = lg2 - (lg2 != 0);
+  arr->data = (uintptr_t)data | bits;
+}
+
+UPB_INLINE size_t _upb_Array_ElemSizeLg2(const upb_Array* arr) {
+  const size_t bits = arr->data & _UPB_ARRAY_MASK_LG2;
+  const size_t lg2 = bits + (bits != 0);
+  return lg2;
 }
 
 UPB_INLINE const void* _upb_array_constptr(const upb_Array* arr) {
-  _upb_Array_ElementSizeLg2(arr);  // Check assertion.
-  return (void*)(arr->data & ~(uintptr_t)7);
-}
-
-UPB_INLINE uintptr_t _upb_array_tagptr(void* ptr, int elem_size_lg2) {
-  UPB_ASSERT(elem_size_lg2 <= 4);
-  return (uintptr_t)ptr | elem_size_lg2;
+  _upb_Array_ElemSizeLg2(arr);  // Check assertions.
+  return (void*)(arr->data & ~(uintptr_t)_UPB_ARRAY_MASK_ALL);
 }
 
 UPB_INLINE void* _upb_array_ptr(upb_Array* arr) {
   return (void*)_upb_array_constptr(arr);
 }
 
-UPB_INLINE uintptr_t _upb_tag_arrptr(void* ptr, int elem_size_lg2) {
-  UPB_ASSERT(elem_size_lg2 <= 4);
-  UPB_ASSERT(((uintptr_t)ptr & 7) == 0);
-  return (uintptr_t)ptr | (unsigned)elem_size_lg2;
-}
-
 UPB_INLINE upb_Array* _upb_Array_New(upb_Arena* a, size_t init_capacity,
                                      int elem_size_lg2) {
+  UPB_ASSERT(elem_size_lg2 != 1);
   UPB_ASSERT(elem_size_lg2 <= 4);
   const size_t arr_size = UPB_ALIGN_UP(sizeof(upb_Array), UPB_MALLOC_ALIGN);
   const size_t bytes = arr_size + (init_capacity << elem_size_lg2);
   upb_Array* arr = (upb_Array*)upb_Arena_Malloc(a, bytes);
   if (!arr) return NULL;
-  arr->data = _upb_tag_arrptr(UPB_PTR_AT(arr, arr_size, void), elem_size_lg2);
+  _upb_Array_SetTaggedPtr(arr, UPB_PTR_AT(arr, arr_size, void), elem_size_lg2);
   arr->size = 0;
   arr->capacity = init_capacity;
   return arr;
@@ -2650,7 +2660,7 @@
 UPB_INLINE void _upb_Array_Set(upb_Array* arr, size_t i, const void* data,
                                size_t elem_size) {
   UPB_ASSERT(i < arr->size);
-  UPB_ASSERT(elem_size == 1U << _upb_Array_ElementSizeLg2(arr));
+  UPB_ASSERT(elem_size == 1U << _upb_Array_ElemSizeLg2(arr));
   char* arr_data = (char*)_upb_array_ptr(arr);
   memcpy(arr_data + (i * elem_size), data, elem_size);
 }
@@ -2663,6 +2673,10 @@
 } /* extern "C" */
 #endif
 
+#undef _UPB_ARRAY_MASK_IMM
+#undef _UPB_ARRAY_MASK_LG2
+#undef _UPB_ARRAY_MASK_ALL
+
 
 #endif /* UPB_MESSAGE_INTERNAL_ARRAY_H_ */