diff --git a/src/crypto/astrobwt/AstroBWT.cpp b/src/crypto/astrobwt/AstroBWT.cpp
index 29e34ecff..47949e4c6 100644
--- a/src/crypto/astrobwt/AstroBWT.cpp
+++ b/src/crypto/astrobwt/AstroBWT.cpp
@@ -48,7 +48,7 @@ static bool astrobwtInitialized = false;
 static bool hasAVX2 = false;
 
 extern "C"
-#ifdef __GNUC__
+#ifndef _MSC_VER
 __attribute__((ms_abi))
 #endif
 void SHA3_256_AVX2_ASM(const void* in, size_t inBytes, void* out);
diff --git a/src/crypto/astrobwt/sha3_256_avx2.S b/src/crypto/astrobwt/sha3_256_avx2.S
index 511294d3a..16dba72f1 100644
--- a/src/crypto/astrobwt/sha3_256_avx2.S
+++ b/src/crypto/astrobwt/sha3_256_avx2.S
@@ -40,6 +40,9 @@
 
 .global DECL(SHA3_256_AVX2_ASM)
 
+ALIGN 64
+DECL(SHA3_256_AVX2_ASM):
+
 #include "sha3_256_avx2.inc"
 
 KeccakF1600_AVX2_ASM:
diff --git a/src/crypto/astrobwt/sha3_256_avx2.asm b/src/crypto/astrobwt/sha3_256_avx2.asm
index c4d5e409f..f38e09f13 100644
--- a/src/crypto/astrobwt/sha3_256_avx2.asm
+++ b/src/crypto/astrobwt/sha3_256_avx2.asm
@@ -29,6 +29,9 @@
 _SHA3_256_AVX2_ASM SEGMENT PAGE READ EXECUTE
 PUBLIC SHA3_256_AVX2_ASM
 
+ALIGN 64
+SHA3_256_AVX2_ASM:
+
 include sha3_256_avx2.inc
 
 KeccakF1600_AVX2_ASM:
diff --git a/src/crypto/astrobwt/sha3_256_avx2.inc b/src/crypto/astrobwt/sha3_256_avx2.inc
index 3c27a31a8..81753dba9 100644
--- a/src/crypto/astrobwt/sha3_256_avx2.inc
+++ b/src/crypto/astrobwt/sha3_256_avx2.inc
@@ -26,8 +26,6 @@
 ;#   along with this program. If not, see <http://www.gnu.org/licenses/>.
 ;#
 
-ALIGN 64
-SHA3_256_AVX2_ASM:
 	vzeroupper
 
 	mov qword ptr [rsp+8],rbx