diff --git a/src/arch/x86_64/asm.rs b/src/arch/x86_64/asm.rs
index ea78a21..1b43598 100644
--- a/src/arch/x86_64/asm.rs
+++ b/src/arch/x86_64/asm.rs
@@ -10,6 +10,8 @@ pub struct Asm {
 #[derive(Clone, Copy)]
 pub enum Instr {
     Mov { dst: RegMode, src: RegImmMem },
+    // TODO: horrible
+    MemMov { reg: RegMode, offset: u64, val: u64 },
     Int(u8),
     Call(Symbol),
     CallMem(Symbol),
@@ -45,6 +47,18 @@ impl From<u64> for RegImmMem {
     }
 }
 
+impl From<i64> for RegImmMem {
+    fn from(value: i64) -> Self {
+        Self::Imm(value as u64)
+    }
+}
+
+impl From<i32> for RegImmMem {
+    fn from(value: i32) -> Self {
+        Self::Imm(value as u32 as u64)
+    }
+}
+
 mod fns {
     use super::*;
     pub fn mov(dst: RegMode, src: impl Into<RegImmMem>) -> Instr {
diff --git a/src/arch/x86_64/encode.rs b/src/arch/x86_64/encode.rs
index cd94a6d..264ff36 100644
--- a/src/arch/x86_64/encode.rs
+++ b/src/arch/x86_64/encode.rs
@@ -110,6 +110,18 @@ impl Encoder<'_> {
         Ok(())
     }
 
+    pub fn mem_mov(&mut self, reg: RegMode, offset: u64, val: u64) {
+        assert!(offset <= u8::MAX as u64);
+        assert!(val <= u32::MAX as u64);
+        self.data
+            .extend([0x48 | ((reg.gt8() as u8) << 2), 0xc7, 0x40 | reg.base()]);
+        if reg.reg == rsp.reg {
+            self.data.push(0x24)
+        }
+        self.data.push(offset as u8);
+        self.data.extend((val as u32).to_le_bytes());
+    }
+
     pub fn lea(&mut self, dst: RegMode, sym: Symbol) {
         self.data.extend([
             0x48 | ((dst.gt8() as u8) << 2),
@@ -184,6 +196,7 @@ impl Encoder<'_> {
     pub fn asm(&mut self, instr: Instr) -> Result<(), CompilerMsg> {
         match instr {
             Instr::Mov { dst, src } => self.mov(dst, src)?,
+            Instr::MemMov { reg, offset, val } => self.mem_mov(reg, offset, val),
             Instr::Int(code) => self.int(code),
             Instr::Syscall => self.syscall(),
             Instr::Lea { dst, sym } => self.lea(dst, sym),
diff --git a/src/arch/x86_64/reg.rs b/src/arch/x86_64/reg.rs
index e161f60..ea3a1e4 100644
--- a/src/arch/x86_64/reg.rs
+++ b/src/arch/x86_64/reg.rs
@@ -1,4 +1,4 @@
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, PartialEq)]
 pub struct Reg(u8);
 
 #[derive(Clone, Copy)]
diff --git a/src/arch/x86_64/test/bin.rs b/src/arch/x86_64/test/bin.rs
index 82af65b..1544270 100644
--- a/src/arch/x86_64/test/bin.rs
+++ b/src/arch/x86_64/test/bin.rs
@@ -79,10 +79,33 @@ fn windows() {
     let mut program = Program::<X86_64>::default();
     let [get_std_handle, write_file, exit_process] =
         program.external("KERNEL32.dll", ["GetStdHandle", "WriteFile", "ExitProcess"]);
+    let text = b"Hello world!\n";
+    let text_sym = program.ro_data("hello_en", text);
+    let written = program.ro_data("written", [0; 4]);
     let entry = program.func(
         "main",
         [BInstr::Asm(Asm {
-            instrs: vec![Instr::Sub, mov(ecx, 40), Instr::CallMem(exit_process)],
+            instrs: vec![
+                Instr::Sub,
+                // stdout
+                mov(ecx, -11),
+                Instr::CallMem(get_std_handle),
+                // write
+                mov(rcx, rax),
+                lea(rdx, text_sym),
+                mov(r8d, text.len() as u64),
+                lea(r9, written),
+                Instr::MemMov {
+                    reg: rsp,
+                    offset: 0x20,
+                    val: 0,
+                },
+                // mov qword [rsp+32], 0
+                Instr::CallMem(write_file),
+                // exit
+                mov(ecx, 39),
+                Instr::CallMem(exit_process),
+            ],
         })],
     );
     program.entry = Some(entry);
diff --git a/src/arch/x86_64/test/reg.rs b/src/arch/x86_64/test/reg.rs
index 5fb6059..28e15f0 100644
--- a/src/arch/x86_64/test/reg.rs
+++ b/src/arch/x86_64/test/reg.rs
@@ -40,15 +40,15 @@ fn reg_reg() {
 fn reg_imm() {
     eq(
         [0x49, 0xbf, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(r15, 0x123456789abcdef0),
+        mov(r15, 0x123456789abcdef0u64),
     );
     eq(
         [0x49, 0xb8, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(r8, 0x123456789abcdef0),
+        mov(r8, 0x123456789abcdef0u64),
     );
     eq(
         [0x49, 0xb9, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(r9, 0x123456789abcdef0),
+        mov(r9, 0x123456789abcdef0u64),
     );
     eq([0x41, 0xb9, 0x78, 0x56, 0x34, 0x12], mov(r9d, 0x12345678));
     eq([0x66, 0x41, 0xb9, 0x34, 0x12], mov(r9w, 0x1234));
@@ -58,15 +58,15 @@ fn reg_imm() {
 
     eq(
         [0x48, 0xb8, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(rax, 0x123456789abcdef0),
+        mov(rax, 0x123456789abcdef0u64),
     );
     eq(
         [0x48, 0xbb, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(rbx, 0x123456789abcdef0),
+        mov(rbx, 0x123456789abcdef0u64),
     );
     eq(
         [0x48, 0xbf, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
-        mov(rdi, 0x123456789abcdef0),
+        mov(rdi, 0x123456789abcdef0u64),
     );
     eq([0xbb, 0x78, 0x56, 0x34, 0x12], mov(ebx, 0x12345678));
     eq([0x66, 0xbb, 0x34, 0x12], mov(bx, 0x1234));
diff --git a/x86_64_test.exe b/x86_64_test.exe
index 14caa1d..6580c3d 100755
Binary files a/x86_64_test.exe and b/x86_64_test.exe differ