diff --git a/av1/common/av1_common_int.h b/av1/common/av1_common_int.h
index a53d8a4..ce1a22c 100644
--- a/av1/common/av1_common_int.h
+++ b/av1/common/av1_common_int.h
@@ -85,8 +85,6 @@
 #define MAX_NUM_TEMPORAL_LAYERS 8
 #define MAX_NUM_SPATIAL_LAYERS 4
 
-#define NUM_QM_VALS 256
-
 /* clang-format off */
 // clang-format seems to think this is a pointer dereference and not a
 // multiplication.
diff --git a/av1/decoder/decodeframe.c b/av1/decoder/decodeframe.c
index 3c52218..2b6ac21 100644
--- a/av1/decoder/decodeframe.c
+++ b/av1/decoder/decodeframe.c
@@ -6697,7 +6697,7 @@
 
       qm_val_t *mat = fund_mat[t][level][c];
       bool coef_repeat_until_end = false;
-      int16_t prev = 32;
+      qm_val_t prev = 32;
       for (int i = 0; i < tx_size_2d[tsize]; i++) {
         const int pos = s->scan[i];
         if (tsize == TX_8X8 && qm_8x8_is_symmetric) {
@@ -6712,17 +6712,18 @@
         if (!coef_repeat_until_end) {
           const int32_t delta = aom_rb_read_svlc(rb);
           // The valid range of quantization matrix coefficients is 1..255.
-          // Therefore the valid range of delta values is -254..254.
-          if (delta < -254 || delta > 254) {
+          // Therefore the valid range of delta values is -254..254. Because of
+          // the % 256 operation, the valid range of delta values can be reduced
+          // to -128..127 to shorten the svlc() code.
+          if (delta < -128 || delta > 127) {
             aom_internal_error(error_info, AOM_CODEC_CORRUPT_FRAME,
                                "Invalid matrix_coef_delta: %d", delta);
           }
-          const int32_t coef = prev + delta;
-          if (coef == 0 || coef == 256) {
+          const qm_val_t coef = (prev + delta + 256) % 256;
+          if (coef == 0) {
             coef_repeat_until_end = true;
           } else {
-            prev = (coef + NUM_QM_VALS) % NUM_QM_VALS;
-            assert(prev >= 1);
+            prev = coef;
           }
         }
         mat[pos] = prev;
diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index ba20b2c..67858aa 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -5730,17 +5730,16 @@
         int16_t coeff = (symbol_idx == stop_symbol_idx) ? 0 : mat[pos];
         int16_t delta = coeff - prev;
         // The decoder reconstructs the matrix coefficient by calculating
-        // (prev + delta + NUM_QM_VALS) % NUM_QM_VALS. Therefore delta,
-        // delta + NUM_QM_VALS, and delta - NUM_QM_VALS are all equivalent
-        // because they are equal modulo NUM_QM_VALS. If delta + NUM_QM_VALS or
-        // delta - NUM_QM_VALS has a smaller absolute value than delta, it is
-        // likely to have a shorter svlc() code, so we will write it instead.
-        // In other words, for each delta value, we aim to find an equivalent
-        // value (modulo NUM_QM_VALS) that has the shortest svlc() code.
-        if (delta < -(NUM_QM_VALS / 2)) {
-          delta += NUM_QM_VALS;
-        } else if (delta >= NUM_QM_VALS / 2) {
-          delta -= NUM_QM_VALS;
+        // (prev + delta + 256) % 256. Therefore delta, delta + 256, and
+        // delta - 256 are all equivalent because they are equal modulo 256. If
+        // delta + 256 or delta - 256 has a smaller absolute value than delta,
+        // it is likely to have a shorter svlc() code, so we will write it
+        // instead. In other words, for each delta value, we aim to find an
+        // equivalent value (modulo 256) that has the shortest svlc() code.
+        if (delta < -128) {
+          delta += 256;
+        } else if (delta > 127) {
+          delta -= 256;
         }
         aom_wb_write_svlc(wb, delta);
         if (symbol_idx == stop_symbol_idx) {