diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index b5e03c6..b77f038 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -20561,13 +20561,6 @@
 
 #if defined(WUFFS_BASE__CPU_ARCH__X86_64)
 static wuffs_base__empty_struct
-wuffs_adler32__hasher__up_x86_avx2(
-    wuffs_adler32__hasher* self,
-    wuffs_base__slice_u8 a_x);
-#endif  // defined(WUFFS_BASE__CPU_ARCH__X86_64)
-
-#if defined(WUFFS_BASE__CPU_ARCH__X86_64)
-static wuffs_base__empty_struct
 wuffs_adler32__hasher__up_x86_sse42(
     wuffs_adler32__hasher* self,
     wuffs_base__slice_u8 a_x);
@@ -20688,9 +20681,6 @@
         wuffs_base__cpu_arch__have_arm_neon() ? &wuffs_adler32__hasher__up_arm_neon :
 #endif
 #if defined(WUFFS_BASE__CPU_ARCH__X86_64)
-        wuffs_base__cpu_arch__have_x86_avx2() ? &wuffs_adler32__hasher__up_x86_avx2 :
-#endif
-#if defined(WUFFS_BASE__CPU_ARCH__X86_64)
         wuffs_base__cpu_arch__have_x86_sse42() ? &wuffs_adler32__hasher__up_x86_sse42 :
 #endif
         self->private_impl.choosy_up);
@@ -20879,96 +20869,6 @@
 #endif  // defined(WUFFS_BASE__CPU_ARCH__ARM_NEON)
 // ‼ WUFFS MULTI-FILE SECTION -arm_neon
 
-// ‼ WUFFS MULTI-FILE SECTION +x86_avx2
-// -------- func adler32.hasher.up_x86_avx2
-
-#if defined(WUFFS_BASE__CPU_ARCH__X86_64)
-WUFFS_BASE__MAYBE_ATTRIBUTE_TARGET("pclmul,popcnt,sse4.2,avx2")
-static wuffs_base__empty_struct
-wuffs_adler32__hasher__up_x86_avx2(
-    wuffs_adler32__hasher* self,
-    wuffs_base__slice_u8 a_x) {
-  uint32_t v_s1 = 0;
-  uint32_t v_s2 = 0;
-  wuffs_base__slice_u8 v_remaining = {0};
-  wuffs_base__slice_u8 v_p = {0};
-  __m256i v_zeroes = {0};
-  __m256i v_ones = {0};
-  __m256i v_weights = {0};
-  __m256i v_q = {0};
-  __m256i v_v1 = {0};
-  __m256i v_v2 = {0};
-  __m256i v_v2j = {0};
-  __m256i v_v2k = {0};
-  __m128i v_h1 = {0};
-  __m128i v_h2 = {0};
-  uint32_t v_num_iterate_bytes = 0;
-  uint64_t v_tail_index = 0;
-
-  v_zeroes = _mm256_set1_epi16((int16_t)(0));
-  v_ones = _mm256_set1_epi16((int16_t)(1));
-  v_weights = _mm256_set_epi8((int8_t)(1), (int8_t)(2), (int8_t)(3), (int8_t)(4), (int8_t)(5), (int8_t)(6), (int8_t)(7), (int8_t)(8), (int8_t)(9), (int8_t)(10), (int8_t)(11), (int8_t)(12), (int8_t)(13), (int8_t)(14), (int8_t)(15), (int8_t)(16), (int8_t)(17), (int8_t)(18), (int8_t)(19), (int8_t)(20), (int8_t)(21), (int8_t)(22), (int8_t)(23), (int8_t)(24), (int8_t)(25), (int8_t)(26), (int8_t)(27), (int8_t)(28), (int8_t)(29), (int8_t)(30), (int8_t)(31), (int8_t)(32));
-  v_s1 = ((self->private_impl.f_state) & 0xFFFF);
-  v_s2 = ((self->private_impl.f_state) >> (32 - (16)));
-  while (((uint64_t)(a_x.len)) > 0) {
-    v_remaining = wuffs_base__slice_u8__subslice_j(a_x, 0);
-    if (((uint64_t)(a_x.len)) > 5536) {
-      v_remaining = wuffs_base__slice_u8__subslice_i(a_x, 5536);
-      a_x = wuffs_base__slice_u8__subslice_j(a_x, 5536);
-    }
-    v_num_iterate_bytes = ((uint32_t)((((uint64_t)(a_x.len)) & 4294967264)));
-    v_s2 += ((uint32_t)(v_s1 * v_num_iterate_bytes));
-    v_v1 = _mm256_setzero_si256();
-    v_v2j = _mm256_setzero_si256();
-    v_v2k = _mm256_setzero_si256();
-    {
-      wuffs_base__slice_u8 i_slice_p = a_x;
-      v_p.ptr = i_slice_p.ptr;
-      v_p.len = 32;
-      uint8_t* i_end0_p = v_p.ptr + (((i_slice_p.len - (size_t)(v_p.ptr - i_slice_p.ptr)) / 32) * 32);
-      while (v_p.ptr < i_end0_p) {
-        v_q = _mm256_lddqu_si256((const __m256i*)(const void*)(v_p.ptr));
-        v_v2j = _mm256_add_epi32(v_v2j, v_v1);
-        v_v1 = _mm256_add_epi32(v_v1, _mm256_sad_epu8(v_q, v_zeroes));
-        v_v2k = _mm256_add_epi32(v_v2k, _mm256_madd_epi16(v_ones, _mm256_maddubs_epi16(v_q, v_weights)));
-        v_p.ptr += 32;
-      }
-      v_p.len = 0;
-    }
-    v_h1 = _mm_add_epi32(_mm256_extracti128_si256(v_v1, (int32_t)(0)), _mm256_extracti128_si256(v_v1, (int32_t)(1)));
-    v_h1 = _mm_add_epi32(v_h1, _mm_shuffle_epi32(v_h1, (int32_t)(177)));
-    v_h1 = _mm_add_epi32(v_h1, _mm_shuffle_epi32(v_h1, (int32_t)(78)));
-    v_s1 += ((uint32_t)(_mm_cvtsi128_si32(v_h1)));
-    v_v2 = _mm256_add_epi32(v_v2k, _mm256_slli_epi32(v_v2j, (int32_t)(5)));
-    v_h2 = _mm_add_epi32(_mm256_extracti128_si256(v_v2, (int32_t)(0)), _mm256_extracti128_si256(v_v2, (int32_t)(1)));
-    v_h2 = _mm_add_epi32(v_h2, _mm_shuffle_epi32(v_h2, (int32_t)(177)));
-    v_h2 = _mm_add_epi32(v_h2, _mm_shuffle_epi32(v_h2, (int32_t)(78)));
-    v_s2 += ((uint32_t)(_mm_cvtsi128_si32(v_h2)));
-    v_tail_index = (((uint64_t)(a_x.len)) & 18446744073709551584u);
-    if (v_tail_index < ((uint64_t)(a_x.len))) {
-      {
-        wuffs_base__slice_u8 i_slice_p = wuffs_base__slice_u8__subslice_i(a_x, v_tail_index);
-        v_p.ptr = i_slice_p.ptr;
-        v_p.len = 1;
-        uint8_t* i_end0_p = i_slice_p.ptr + i_slice_p.len;
-        while (v_p.ptr < i_end0_p) {
-          v_s1 += ((uint32_t)(v_p.ptr[0]));
-          v_s2 += v_s1;
-          v_p.ptr += 1;
-        }
-        v_p.len = 0;
-      }
-    }
-    v_s1 %= 65521;
-    v_s2 %= 65521;
-    a_x = v_remaining;
-  }
-  self->private_impl.f_state = (((v_s2 & 65535) << 16) | (v_s1 & 65535));
-  return wuffs_base__make_empty_struct();
-}
-#endif  // defined(WUFFS_BASE__CPU_ARCH__X86_64)
-// ‼ WUFFS MULTI-FILE SECTION -x86_avx2
-
 // ‼ WUFFS MULTI-FILE SECTION +x86_sse42
 // -------- func adler32.hasher.up_x86_sse42
 
diff --git a/std/adler32/common_adler32.wuffs b/std/adler32/common_adler32.wuffs
index c3b4c08..eb2a93b 100644
--- a/std/adler32/common_adler32.wuffs
+++ b/std/adler32/common_adler32.wuffs
@@ -27,7 +27,6 @@
 		this.state = 1
 		choose up = [
 			up_arm_neon,
-			up_x86_avx2,
 			up_x86_sse42]
 	}
 	this.up!(x: args.x)
diff --git a/std/adler32/common_up_x86_avx2.wuffs b/std/adler32/common_up_x86_avx2.wuffs
deleted file mode 100644
index a8209f2..0000000
--- a/std/adler32/common_up_x86_avx2.wuffs
+++ /dev/null
@@ -1,179 +0,0 @@
-// Copyright 2021 The Wuffs Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//    https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-pri func hasher.up_x86_avx2!(x: slice base.u8),
-	choose cpu_arch >= x86_avx2,
-{
-	// These variables are the same as the non-SIMD version.
-	var s1        : base.u32
-	var s2        : base.u32
-	var remaining : slice base.u8
-	var p         : slice base.u8
-
-	// The remaining variables are specific to the SIMD version.
-
-	var util    : base.x86_avx2_utility
-	var zeroes  : base.x86_m256i
-	var ones    : base.x86_m256i
-	var weights : base.x86_m256i
-	var q       : base.x86_m256i
-	var v1      : base.x86_m256i
-	var v2      : base.x86_m256i
-	var v2j     : base.x86_m256i
-	var v2k     : base.x86_m256i
-
-	var h1 : base.x86_m128i
-	var h2 : base.x86_m128i
-
-	var num_iterate_bytes : base.u32
-	var tail_index        : base.u64
-
-	// zeroes and ones are uniform u16×8 vectors.
-	zeroes = util.make_m256i_repeat_u16(a: 0)
-	ones = util.make_m256i_repeat_u16(a: 1)
-
-	// weights form the sequence 32, 31, 30, ..., 1.
-	weights = util.make_m256i_multiple_u8(
-		a00: 0x20, a01: 0x1F, a02: 0x1E, a03: 0x1D,
-		a04: 0x1C, a05: 0x1B, a06: 0x1A, a07: 0x19,
-		a08: 0x18, a09: 0x17, a10: 0x16, a11: 0x15,
-		a12: 0x14, a13: 0x13, a14: 0x12, a15: 0x11,
-		a16: 0x10, a17: 0x0F, a18: 0x0E, a19: 0x0D,
-		a20: 0x0C, a21: 0x0B, a22: 0x0A, a23: 0x09,
-		a24: 0x08, a25: 0x07, a26: 0x06, a27: 0x05,
-		a28: 0x04, a29: 0x03, a30: 0x02, a31: 0x01)
-
-	// Decompose this.state.
-	s1 = this.state.low_bits(n: 16)
-	s2 = this.state.high_bits(n: 16)
-
-	// Just like the non-SIMD version, loop over args.x up to almost-5552 bytes
-	// at a time. The slightly smaller 5536 is the largest multiple of 32 less
-	// than non-SIMD's 5552.
-	while args.x.length() > 0 {
-		remaining = args.x[.. 0]
-		if args.x.length() > 5536 {
-			remaining = args.x[5536 ..]
-			args.x = args.x[.. 5536]
-		}
-
-		// The s1 state is the sum of the input bytes and the s2 state is the
-		// sum of the s1 state at each 1-byte step. Inside the iterate loop
-		// below, but starting fresh at each outer while loop iteration, s1
-		// consists of three parts (called s1i, s1j and s1k):
-		//  - s1i: the initial value, before any 32-byte iterations.
-		//  - s1j: the total contribution from previous 32-byte iterations.
-		//  - s1k: the contribution due to the current 32-byte iteration.
-		//
-		// The upcoming iterate loop (at 32 bytes per iteration) encompasses
-		// num_iterate_bytes 1-byte steps. We hoist the total s1i contribution,
-		// (s1i * num_iterate_bytes) out here.
-		num_iterate_bytes = (args.x.length() & 0xFFFF_FFE0) as base.u32
-		s2 ~mod+= (s1 ~mod* num_iterate_bytes)
-
-		// Zero-initialize some u32×8 vectors associated with the two state
-		// variables s1 and s2. The iterate loop accumulates eight parallel u32
-		// sums in each vector. A post-iterate step merges the eight u32 sums
-		// into a single u32 sum.
-		v1 = util.make_m256i_zeroes()
-		v2j = util.make_m256i_zeroes()
-		v2k = util.make_m256i_zeroes()
-
-		// The inner loop.
-		iterate (p = args.x)(length: 32, advance: 32, unroll: 1) {
-			// AVX2 works with 32-byte registers.
-			//
-			// Let q = [u8×32: p00, p01, p02, ..., p31]
-			q = util.make_m256i_slice256(a: p)
-
-			// For v2j, we need to calculate the sums of the s1j terms for each
-			// of p's 32 elements. This is simply 32 times the same number,
-			// that number being the sum of v1's eight u32 accumulators. We add
-			// v1 now and multiply by 32 later, outside the inner loop.
-			v2j = v2j._mm256_add_epi32(b: v1)
-
-			// For v1, we need to add the elements of p. Computing the sum of
-			// absolute differences (_mm256_sad_epu8) with zero just sums the
-			// elements. q._mm256_sad_epu8(b: zeroes) equals
-			//   [u64×4: p00 + p01 + ... + p07, p08 + p09 + ... + p15,
-			//           p16 + p17 + ... + p23, p24 + p25 + ... + p31]
-			// This is equivalent (little-endian) to:
-			//   [u32×8: p00 + p01 + ... + p07, 0, p08 + p09 + ... + p15, 0,
-			//           p16 + p17 + ... + p23, 0, p24 + p25 + ... + p31, 0]
-			// We accumulate those "sum of q's elements" in v1.
-			v1 = v1._mm256_add_epi32(b: q._mm256_sad_epu8(b: zeroes))
-
-			// For v2k, we need to calculate a weighted sum: ((32 * p00) + (31
-			// * p01) + (30 * p02) + ... + (1 * p31)).
-			//
-			// The _mm256_maddubs_epi16 call (vertically multiply u8 columns
-			// and then horizontally sum u16 pairs) produces:
-			//   [u16×16: ((32*p00)+(31*p01)),
-			//            ((30*p02)+(29*p03)),
-			//            ...
-			//            (( 2*p30)+( 1*p31))]
-			//
-			// The ones._mm256_madd_epi16(b: etc) call is a multiply-add (note
-			// that it's "madd" not "add"). Multiplying by 1 is a no-op, so
-			// this sums u16 pairs to produce u32 values:
-			//   [u32×8: (((32*p00)+(31*p01)+(30*p02)+(29*p03)),
-			//           (((28*p04)+(27*p05)+(26*p06)+(25*p07)),
-			//           ...
-			//           ((( 4*p28)+( 3*p29)+( 2*p30)+( 1*p31))]
-			v2k = v2k._mm256_add_epi32(b: ones._mm256_madd_epi16(
-				b: q._mm256_maddubs_epi16(b: weights)))
-		}
-
-		// Merge the eight parallel u32 sums (v1) into the single u32 sum (s1).
-		// First, merge the 256-bit (u32×8) v1 into the 128-bit (u32×4) h1.
-		h1 = v1._mm256_extracti128_si256(imm8: 0)._mm_add_epi32(
-			b: v1._mm256_extracti128_si256(imm8: 1))
-
-		// Starting with a u32×4 vector [x0, x1, x2, x3]:
-		//  - shuffling with 0b1011_0001 gives [x1, x0, x3, x2].
-		//  - adding gives [x0+x1, x0+x1, x2+x3, x2+x3].
-		//  - shuffling with 0b0100_1110 gives [x2+x3, x2+x3, x0+x1, x0+x1].
-		//  - adding gives [x0+x1+x2+x3, ditto, ditto, ditto].
-		// The truncate_u32 call extracts the first u32: x0+x1+x2+x3.
-		h1 = h1._mm_add_epi32(b: h1._mm_shuffle_epi32(imm8: 0b1011_0001))
-		h1 = h1._mm_add_epi32(b: h1._mm_shuffle_epi32(imm8: 0b0100_1110))
-		s1 ~mod+= h1.truncate_u32()
-
-		// Combine v2j and v2k. The slli (shift logical left immediate) by 5
-		// multiplies v2j's eight u32 elements each by 32, alluded to earlier.
-		v2 = v2k._mm256_add_epi32(b: v2j._mm256_slli_epi32(imm8: 5))
-
-		// Similarly merge v2 (a u32×8 vector) into s2 (a u32 scalar).
-		h2 = v2._mm256_extracti128_si256(imm8: 0)._mm_add_epi32(
-			b: v2._mm256_extracti128_si256(imm8: 1))
-		h2 = h2._mm_add_epi32(b: h2._mm_shuffle_epi32(imm8: 0b1011_0001))
-		h2 = h2._mm_add_epi32(b: h2._mm_shuffle_epi32(imm8: 0b0100_1110))
-		s2 ~mod+= h2.truncate_u32()
-
-		// Handle the tail of args.x that wasn't a complete 32-byte chunk.
-		tail_index = args.x.length() & 0xFFFF_FFFF_FFFF_FFE0  // And-not 32.
-		if tail_index < args.x.length() {
-			iterate (p = args.x[tail_index ..])(length: 1, advance: 1, unroll: 1) {
-				s1 ~mod+= p[0] as base.u32
-				s2 ~mod+= s1
-			}
-		}
-
-		// The rest of this function is the same as the non-SIMD version.
-		s1 %= 65521
-		s2 %= 65521
-		args.x = remaining
-	} endwhile
-	this.state = ((s2 & 0xFFFF) << 16) | (s1 & 0xFFFF)
-}