diff --git a/gromacs/includes/simd/avx512_double.h b/gromacs/includes/simd/avx512_double.h
index 18d67eb..3777c0c 100644
--- a/gromacs/includes/simd/avx512_double.h
+++ b/gromacs/includes/simd/avx512_double.h
@@ -40,6 +40,7 @@ static inline MD_SIMD_MASK simd_mask_cond_lt(MD_SIMD_FLOAT a, MD_SIMD_FLOAT b) {
 static inline MD_SIMD_MASK simd_mask_from_u32(unsigned int a) { return _cvtu32_mask8(a); }
 static inline unsigned int simd_mask_to_u32(MD_SIMD_MASK a) { return _cvtmask8_u32(a); }
 static inline MD_SIMD_FLOAT simd_load(MD_FLOAT *p) { return _mm512_load_pd(p); }
+static inline MD_SIMD_FLOAT select_by_mask(MD_SIMD_FLOAT a, MD_SIMD_MASK m) { return _mm512_mask_mov_pd(_mm512_setzero_pd(), m, a); }
 static inline MD_FLOAT simd_h_reduce_sum(MD_SIMD_FLOAT a) {
     MD_SIMD_FLOAT x = _mm512_add_pd(a, _mm512_shuffle_f64x2(a, a, 0xee));
     x = _mm512_add_pd(x, _mm512_shuffle_f64x2(x, x, 0x11));
@@ -94,3 +95,17 @@ static inline MD_FLOAT simd_h_dual_incr_reduced_sum(MD_FLOAT *m, MD_SIMD_FLOAT v
     t0 = _mm512_add_pd(t0, _mm512_permutex_pd(t0, 0xb1));
     return _mm_cvtsd_f64(_mm512_castpd512_pd128(t0));
 }
+
+inline void simd_h_decr(MD_FLOAT *m, MD_SIMD_FLOAT a) {
+    __m256d t;
+    a = _mm512_add_pd(a, _mm512_shuffle_f64x2(a, a, 0xee));
+    t = _mm256_load_pd(m);
+    t = _mm256_sub_pd(t, _mm512_castpd512_pd256(a));
+    _mm256_store_pd(m, t);
+}
+
+static inline void simd_h_decr3(MD_FLOAT *m, MD_SIMD_FLOAT a0, MD_SIMD_FLOAT a1, MD_SIMD_FLOAT a2) {
+    simd_h_decr(m, a0);
+    simd_h_decr(m + CLUSTER_N, a1);
+    simd_h_decr(m + CLUSTER_N * 2, a2);
+}
diff --git a/gromacs/includes/simd/avx512_float.h b/gromacs/includes/simd/avx512_float.h
index 104ad2c..1f7c0ee 100644
--- a/gromacs/includes/simd/avx512_float.h
+++ b/gromacs/includes/simd/avx512_float.h
@@ -95,6 +95,6 @@ inline void simd_h_decr(MD_FLOAT *m, MD_SIMD_FLOAT a) {
 
 static inline void simd_h_decr3(MD_FLOAT *m, MD_SIMD_FLOAT a0, MD_SIMD_FLOAT a1, MD_SIMD_FLOAT a2) {
     simd_h_decr(m, a0);
-    simd_h_decr(m + CLUSTER_M, a1);
-    simd_h_decr(m + CLUSTER_M * 2, a2);
+    simd_h_decr(m + CLUSTER_N, a1);
+    simd_h_decr(m + CLUSTER_N * 2, a2);
 }