diff --git a/faiss/impl/scalar_quantizer/sq-avx512.cpp b/faiss/impl/scalar_quantizer/sq-avx512.cpp
index f85f8bbb8c..07d994f712 100644
--- a/faiss/impl/scalar_quantizer/sq-avx512.cpp
+++ b/faiss/impl/scalar_quantizer/sq-avx512.cpp
@@ -382,24 +382,54 @@ struct DistanceComputerByte<Similarity, SIMDLevel::AVX512>
 
     int compute_code_distance(const uint8_t* code1, const uint8_t* code2)
             const {
-        // compute 16 lanes of 32-bit products (16-bytes) at once for
+        // compute 32 lanes of 16-bit products (32-bytes) at once for
         // the supported metrics
         __m512i accu = _mm512_setzero_si512();
-        constexpr int kLanes = 16;
-        for (int i = 0; i < d; i += kLanes) {
-            __m128i c1 = _mm_loadu_si128((__m128i*)(code1 + i));
-            __m128i c2 = _mm_loadu_si128((__m128i*)(code2 + i));
-            __m512i c1i = _mm512_cvtepu8_epi32(c1);
-            __m512i c2i = _mm512_cvtepu8_epi32(c2);
-
-            __m512i v;
+        constexpr int kLanes = 32;
+        int i = 0;
+        for (; i + kLanes <= d; i += kLanes) {
+            __m256i c1 = _mm256_loadu_epi8(code1 + i);
+            __m256i c2 = _mm256_loadu_epi8(code2 + i);
+            __m512i c1i16 = _mm512_cvtepu8_epi16(c1);
+            __m512i c2i16 = _mm512_cvtepu8_epi16(c2);
+#ifdef __AVX512VNNI__
             if (Sim::metric_type == METRIC_INNER_PRODUCT) {
-                v = _mm512_mullo_epi32(c1i, c2i);
+                accu = _mm512_dpwssd_epi32(accu, c1i16, c2i16);
             } else {
-                __m512i diff = _mm512_sub_epi32(c1i, c2i);
-                v = _mm512_mullo_epi32(diff, diff);
+                __m512i diff = _mm512_sub_epi16(c1i16, c2i16);
+                accu = _mm512_dpwssd_epi32(accu, diff, diff);
             }
-            accu = _mm512_add_epi32(accu, v);
+#else
+            if (Sim::metric_type == METRIC_INNER_PRODUCT) {
+                accu = _mm512_add_epi32(accu, _mm512_madd_epi16(c1i16, c2i16));
+            } else {
+                __m512i diff = _mm512_sub_epi16(c1i16, c2i16);
+                accu = _mm512_add_epi32(accu, _mm512_madd_epi16(diff, diff));
+            }
+#endif
+        }
+        // tail handling for dimensions not divisible by 32
+        if (i < d) {
+            __mmask32 mask = (__mmask32)((1ULL << (d - i)) - 1ULL);
+            __m256i c1 = _mm256_maskz_loadu_epi8(mask, code1 + i);
+            __m256i c2 = _mm256_maskz_loadu_epi8(mask, code2 + i);
+            __m512i c1i16 = _mm512_cvtepu8_epi16(c1);
+            __m512i c2i16 = _mm512_cvtepu8_epi16(c2);
+#ifdef __AVX512VNNI__
+            if (Sim::metric_type == METRIC_INNER_PRODUCT) {
+                accu = _mm512_dpwssd_epi32(accu, c1i16, c2i16);
+            } else {
+                __m512i diff = _mm512_sub_epi16(c1i16, c2i16);
+                accu = _mm512_dpwssd_epi32(accu, diff, diff);
+            }
+#else
+            if (Sim::metric_type == METRIC_INNER_PRODUCT) {
+                accu = _mm512_add_epi32(accu, _mm512_madd_epi16(c1i16, c2i16));
+            } else {
+                __m512i diff = _mm512_sub_epi16(c1i16, c2i16);
+                accu = _mm512_add_epi32(accu, _mm512_madd_epi16(diff, diff));
+            }
+#endif
         }
         return _mm512_reduce_add_epi32(accu);
     }