diff --git a/amd64/Development/M0.S b/amd64/Development/M0.S
index f4c706f..fce0f9f 100644
--- a/amd64/Development/M0.S
+++ b/amd64/Development/M0.S
@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+.intel_syntax
 .global _start
 .text
 
diff --git a/amd64/Development/Makefile b/amd64/Development/Makefile
index 2440fba..6def277 100644
--- a/amd64/Development/Makefile
+++ b/amd64/Development/Makefile
@@ -5,7 +5,7 @@
 targets = kaem-optional hex0 hex1 hex2 catm M0
 
 cc = clang
-cflags = -ffreestanding -MMD -mno-red-zone -std=c11 -target x86_64-unknown-windows -masm=intel
+cflags = -ffreestanding -MMD -mno-red-zone -target x86_64-unknown-windows
 ld = lld-link
 lflags = -subsystem:efi_application -nodefaultlib -dll
 
diff --git a/amd64/Development/catm.S b/amd64/Development/catm.S
index 1c0a0c5..d37d591 100644
--- a/amd64/Development/catm.S
+++ b/amd64/Development/catm.S
@@ -3,7 +3,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-
+.intel_syntax
 .global _start
 .text
 
diff --git a/amd64/Development/hex0.S b/amd64/Development/hex0.S
index be006bb..3dc2650 100644
--- a/amd64/Development/hex0.S
+++ b/amd64/Development/hex0.S
@@ -11,6 +11,7 @@
 # but we need to leave stack space
 # rax, rcx, rdx, r8, r9, r10 and r11 are volatile and can be changed by called function
 
+.intel_syntax
 .global _start
 .text
 
diff --git a/amd64/Development/hex1.S b/amd64/Development/hex1.S
index 1f35088..8a67e5f 100644
--- a/amd64/Development/hex1.S
+++ b/amd64/Development/hex1.S
@@ -6,6 +6,7 @@
 # Some of the functions are deliberately inlined at the slight expense of
 # binary size to avoid tricky jump calculations in hex0 code.
 
+.intel_syntax
 .global _start
 .text
 
diff --git a/amd64/Development/hex2.S b/amd64/Development/hex2.S
index 7b0953f..379f70f 100644
--- a/amd64/Development/hex2.S
+++ b/amd64/Development/hex2.S
@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+.intel_syntax
 .global _start
 .text
 
diff --git a/amd64/Development/kaem-optional.S b/amd64/Development/kaem-optional.S
index 0961953..337a6c2 100644
--- a/amd64/Development/kaem-optional.S
+++ b/amd64/Development/kaem-optional.S
@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+.intel_syntax
 .global _start
 .text