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--- original_noise_math.h
+++ noise_math_optimized.h
@@ -1490,73 +1490,87 @@
     return f;
 }
 
+/* Unsigned arithmetic preserves the Java long wraparound. */
+static inline __attribute__((const, always_inline)) uint64_t
+noiseopt_biome_hash_step(uint64_t v, uint64_t salt) {
+    return v * (v * UINT64_C(6364136223846793005) +
+                UINT64_C(1442695040888963407)) + salt;
+}
+
+/* This comparison idiom maps to hardware MINPD for non-NaN inputs. */
+static inline __attribute__((const, always_inline)) double
+noiseopt_biome_min(double a, double b) {
+    return a > b ? b : a;
+}
+
 __attribute__((const)) uint32_t
 math_biome_access_sample(const int64_t theSeed, const int32_t x, const int32_t y, const int32_t z) {
-    const int32_t var0 = x - 2;
-    const int32_t var1 = y - 2;
-    const int32_t var2 = z - 2;
-    const int32_t var3 = var0 >> 2;
-    const int32_t var4 = var1 >> 2;
-    const int32_t var5 = var2 >> 2;
-    const double var6 = (double) (var0 & 3) / 4.0;
-    const double var7 = (double) (var1 & 3) / 4.0;
-    const double var8 = (double) (var2 & 3) / 4.0;
-    uint32_t var9 = 0;
-    double var10 = DBL_MAX;
+    /* Java integer subtraction wraps modulo 2^32. */
+    const int32_t xx = (int32_t)((uint32_t)x - 2u);
+    const int32_t yy = (int32_t)((uint32_t)y - 2u);
+    const int32_t zz = (int32_t)((uint32_t)z - 2u);
+
+    const int32_t cx = xx >> 2;
+    const int32_t cy = yy >> 2;
+    const int32_t cz = zz >> 2;
+    const double fx = (double)(xx & 3) * 0.25;
+    const double fy = (double)(yy & 3) * 0.25;
+    const double fz = (double)(zz & 3) * 0.25;
+
+    const uint64_t seed = (uint64_t)theSeed;
+    const uint64_t x0 = (uint64_t)(int64_t)cx;
+    const uint64_t x1 = (uint64_t)(int64_t)(cx + 1);
+    const uint64_t y0 = (uint64_t)(int64_t)cy;
+    const uint64_t y1 = (uint64_t)(int64_t)(cy + 1);
+    const uint64_t z0 = (uint64_t)(int64_t)cz;
+    const uint64_t z1 = (uint64_t)(int64_t)(cz + 1);
 
-    double var28s[8];
 
+
+    double distance[8];
 #pragma clang loop vectorize_width(NOISEOPT_DOUBLE_LANES) interleave_count(NOISEOPT_BIOME_INTERLEAVE)
-    for (uint32_t var11 = 0; var11 < 8; ++var11) {
-        uint32_t var12 = var11 & 4;
-        uint32_t var13 = var11 & 2;
-        uint32_t var14 = var11 & 1;
-        int64_t var15 = var12 ? var3 + 1 : var3;
-        int64_t var16 = var13 ? var4 + 1 : var4;
-        int64_t var17 = var14 ? var5 + 1 : var5;
-        double var18 = var12 ? var6 - 1.0 : var6;
-        double var19 = var13 ? var7 - 1.0 : var7;
-        double var20 = var14 ? var8 - 1.0 : var8;
-        int64_t var21 = theSeed * (theSeed * 6364136223846793005L + 1442695040888963407L) + var15;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + var16;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + var17;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + var15;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + var16;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + var17;
-        double var22 = (double) ((var21 >> 24) & 1023) / 1024.0;
-        double var23 = (var22 - 0.5) * 0.9;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + theSeed;
-        double var24 = (double) ((var21 >> 24) & 1023) / 1024.0;
-        double var25 = (var24 - 0.5) * 0.9;
-        var21 = var21 * (var21 * 6364136223846793005L + 1442695040888963407L) + theSeed;
-        double var26 = (double) ((var21 >> 24) & 1023) / 1024.0;
-        double var27 = (var26 - 0.5) * 0.9;
-        double var28 = math_square(var20 + var27) + math_square(var19 + var25) + math_square(var18 + var23);
-        __builtin_assume(!__builtin_isnan(var28) && !__builtin_signbit(var28));
-        var28s[var11] = var28;
+    for (uint32_t i = 0; i < 8; ++i) {
+        const uint64_t ix = (i & 4) ? x1 : x0;
+        const uint64_t iy = (i & 2) ? y1 : y0;
+        const uint64_t iz = (i & 1) ? z1 : z0;
+        const double dx = (i & 4) ? fx - 1.0 : fx;
+        const double dy = (i & 2) ? fy - 1.0 : fy;
+        const double dz = (i & 1) ? fz - 1.0 : fz;
+
+        uint64_t h = noiseopt_biome_hash_step(noiseopt_biome_hash_step(seed, ix), iy);
+        h = noiseopt_biome_hash_step(h, iz);
+        h = noiseopt_biome_hash_step(h, ix);
+        h = noiseopt_biome_hash_step(h, iy);
+        h = noiseopt_biome_hash_step(h, iz);
+
+        const double rx = ((double)((h >> 24) & 1023u) / 1024.0 - 0.5) * 0.9;
+        h = noiseopt_biome_hash_step(h, seed);
+        const double ry = ((double)((h >> 24) & 1023u) / 1024.0 - 0.5) * 0.9;
+        h = noiseopt_biome_hash_step(h, seed);
+        const double rz = ((double)((h >> 24) & 1023u) / 1024.0 - 0.5) * 0.9;
+
+        distance[i] = math_square(dz + rz) + math_square(dy + ry) + math_square(dx + rx);
     }
 
-    // use bmin or use >= produces different asm
-    double m04 = __builtin_fmin(var28s[0], var28s[4]);
-    double m15 = __builtin_fmin(var28s[1], var28s[5]);
-    double m26 = __builtin_fmin(var28s[2], var28s[6]);
-    double m37 = __builtin_fmin(var28s[3], var28s[7]);
-    double m0426 = __builtin_fmin(m04, m26);
-    double m1537 = __builtin_fmin(m15, m37);
-    double minimum = __builtin_fmin(m0426, m1537);
-
-    uint8_t bitmap = (uint8_t)(var28s[0] == minimum)
-               | (uint8_t)((var28s[1] == minimum) << 1)
-               | (uint8_t)((var28s[2] == minimum) << 2)
-               | (uint8_t)((var28s[3] == minimum) << 3)
-               | (uint8_t)((var28s[4] == minimum) << 4)
-               | (uint8_t)((var28s[5] == minimum) << 5)
-               | (uint8_t)((var28s[6] == minimum) << 6)
-               | (uint8_t)((var28s[7] == minimum) << 7);
- 
-    return __builtin_ctz(bitmap);
+    const double m04 = noiseopt_biome_min(distance[0], distance[4]);
+    const double m15 = noiseopt_biome_min(distance[1], distance[5]);
+    const double m26 = noiseopt_biome_min(distance[2], distance[6]);
+    const double m37 = noiseopt_biome_min(distance[3], distance[7]);
+    const double m0426 = noiseopt_biome_min(m04, m26);
+    const double m1537 = noiseopt_biome_min(m15, m37);
+    const double minimum = noiseopt_biome_min(m0426, m1537);
+
+    /* Distances are finite and >= +0.0, so at least one lane matches. */
+    const unsigned mask = ((unsigned)(distance[0] == minimum) << 0)
+                        | ((unsigned)(distance[1] == minimum) << 1)
+                        | ((unsigned)(distance[2] == minimum) << 2)
+                        | ((unsigned)(distance[3] == minimum) << 3)
+                        | ((unsigned)(distance[4] == minimum) << 4)
+                        | ((unsigned)(distance[5] == minimum) << 5)
+                        | ((unsigned)(distance[6] == minimum) << 6)
+                        | ((unsigned)(distance[7] == minimum) << 7);
+    return (uint32_t)__builtin_ctz(mask);
 }
-
 typedef const struct aquifer_data {
     int32_t startX;
     int32_t startY;