diff --git a/src/utils/huffman_encode_utils.c b/src/utils/huffman_encode_utils.c
index 45f758ea..1b18f384 100644
--- a/src/utils/huffman_encode_utils.c
+++ b/src/utils/huffman_encode_utils.c
@@ -139,7 +139,7 @@ static int CompareHuffmanTrees(const void* ptr1, const void* ptr2) {
 
 static void SetBitDepths(const HuffmanTree* const tree,
                          const HuffmanTree* const pool,
-                         uint8_t* const bit_depths, int level) {
+                         uint8_t* WEBP_INDEXABLE const bit_depths, int level) {
   if (tree->pool_index_left >= 0) {
     SetBitDepths(&pool[tree->pool_index_left], pool, bit_depths, level + 1);
     SetBitDepths(&pool[tree->pool_index_right], pool, bit_depths, level + 1);
@@ -170,7 +170,8 @@ static void SetBitDepths(const HuffmanTree* const tree,
 static void GenerateOptimalTree(const uint32_t* const histogram,
                                 int histogram_size, HuffmanTree* tree,
                                 int tree_depth_limit,
-                                uint8_t* const bit_depths) {
+                                uint8_t* WEBP_COUNTED_BY(histogram_size)
+                                    const bit_depths) {
   uint32_t count_min;
   HuffmanTree* tree_pool;
   int tree_size_orig = 0;
diff --git a/src/utils/huffman_encode_utils.h b/src/utils/huffman_encode_utils.h
index 98dc61da..d80f96b1 100644
--- a/src/utils/huffman_encode_utils.h
+++ b/src/utils/huffman_encode_utils.h
@@ -31,9 +31,11 @@ typedef struct {
 
 // Struct to represent the tree codes (depth and bits array).
 typedef struct {
-  int num_symbols;        // Number of symbols.
-  uint8_t* code_lengths;  // Code lengths of the symbols.
-  uint16_t* codes;        // Symbol Codes.
+  int num_symbols;  // Number of symbols.
+  // Code lengths of the symbols.
+  uint8_t* WEBP_COUNTED_BY(num_symbols) code_lengths;
+  // Symbol Codes.
+  uint16_t* WEBP_COUNTED_BY(num_symbols) codes;
 } HuffmanTreeCode;
 
 // Struct to represent the Huffman tree.