diff --git a/src/arch/arm64/Registers.go b/src/arch/arm64/Registers.go
index cf8c5db..088e2b3 100644
--- a/src/arch/arm64/Registers.go
+++ b/src/arch/arm64/Registers.go
@@ -32,8 +32,9 @@ const (
 	X26
 	X27
 	X28
-	X29
-	X30
+	FP // Frame pointer
+	LR // Link register
+	SP // Stack pointer
 )
 
 var SyscallInputRegisters = []cpu.Register{X8, X0, X1, X2, X3, X4, X5}
diff --git a/src/os/linux/elf/ELF.go b/src/os/linux/elf/ELF.go
index 87818dc..fb8b517 100644
--- a/src/os/linux/elf/ELF.go
+++ b/src/os/linux/elf/ELF.go
@@ -45,7 +45,7 @@ func New(code []byte, data []byte) *ELF {
 			Size:                        HeaderSize,
 			ProgramHeaderEntrySize:      ProgramHeaderSize,
 			ProgramHeaderEntryCount:     2,
-			SectionHeaderEntrySize:      SectionHeaderSize,
+			SectionHeaderEntrySize:      0,
 			SectionHeaderEntryCount:     0,
 			SectionNameStringTableIndex: 0,
 		},
diff --git a/src/os/mac/macho/Header.go b/src/os/mac/macho/Header.go
index f7798be..21c0c54 100644
--- a/src/os/mac/macho/Header.go
+++ b/src/os/mac/macho/Header.go
@@ -1,5 +1,7 @@
 package macho
 
+const HeaderSize = 32
+
 // Header contains general information.
 type Header struct {
 	Magic             uint32
diff --git a/src/os/mac/macho/MachO.go b/src/os/mac/macho/MachO.go
index d48281c..a96e37b 100644
--- a/src/os/mac/macho/MachO.go
+++ b/src/os/mac/macho/MachO.go
@@ -24,9 +24,9 @@ func New(code []byte, data []byte) *MachO {
 			Architecture:      CPU_X86_64,
 			MicroArchitecture: 3 | 0x80000000,
 			Type:              TypeExecute,
-			NumCommands:       5,
-			SizeCommands:      72*4 + 184,
-			Flags:             FlagNoUndefs,
+			NumCommands:       4,
+			SizeCommands:      Segment64Size*3 + ThreadSize,
+			Flags:             FlagNoUndefs | FlagNoHeapExecution,
 			Reserved:          0,
 		},
 		Code: code,
@@ -52,33 +52,19 @@ func (m *MachO) Write(writer io.Writer) {
 		InitProt:     0,
 	})
 
-	codePadding := common.Padding(32+m.Header.SizeCommands, config.Align)
+	codePadding := common.Padding(HeaderSize+m.Header.SizeCommands, config.Align)
 	codeEnd := uint64(config.CodeOffset + len(m.Code))
 	dataPadding := common.Padding(codeEnd, config.Align)
 	dataStart := codeEnd + dataPadding
 
-	binary.Write(writer, binary.LittleEndian, &Segment64{
-		LoadCommand:  LcSegment64,
-		Length:       72,
-		Name:         [16]byte{'_', '_', 'H', 'E', 'A', 'D'},
-		Address:      config.BaseAddress,
-		SizeInMemory: config.CodeOffset,
-		Offset:       0,
-		SizeInFile:   config.CodeOffset,
-		NumSections:  0,
-		Flag:         0,
-		MaxProt:      ProtReadable | ProtExecutable,
-		InitProt:     ProtReadable | ProtExecutable,
-	})
-
 	binary.Write(writer, binary.LittleEndian, &Segment64{
 		LoadCommand:  LcSegment64,
 		Length:       72,
 		Name:         [16]byte{'_', '_', 'T', 'E', 'X', 'T'},
-		Address:      config.BaseAddress + config.CodeOffset,
-		SizeInMemory: uint64(len(m.Code)),
-		Offset:       config.CodeOffset,
-		SizeInFile:   uint64(len(m.Code)),
+		Address:      config.BaseAddress,
+		SizeInMemory: config.CodeOffset + uint64(len(m.Code)),
+		Offset:       0,
+		SizeInFile:   config.CodeOffset + uint64(len(m.Code)),
 		NumSections:  0,
 		Flag:         0,
 		MaxProt:      ProtReadable | ProtExecutable,
@@ -103,31 +89,30 @@ func (m *MachO) Write(writer io.Writer) {
 		LoadCommand: LcUnixthread,
 		Len:         184,
 		Type:        0x4,
-	})
-
-	binary.Write(writer, binary.LittleEndian, []uint32{
-		42,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		config.BaseAddress + config.CodeOffset, 0,
-		0, 0,
-		0, 0,
-		0, 0,
-		0, 0,
+		Data: [43]uint32{
+			42,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			config.BaseAddress + config.CodeOffset, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+			0, 0,
+		},
 	})
 
 	writer.Write(bytes.Repeat([]byte{0}, int(codePadding)))
diff --git a/src/os/mac/macho/Segment64.go b/src/os/mac/macho/Segment64.go
index 382e18f..1f611f0 100644
--- a/src/os/mac/macho/Segment64.go
+++ b/src/os/mac/macho/Segment64.go
@@ -1,5 +1,7 @@
 package macho
 
+const Segment64Size = 72
+
 // Segment64 is a segment load command.
 type Segment64 struct {
 	LoadCommand
diff --git a/src/os/mac/macho/Thread.go b/src/os/mac/macho/Thread.go
index 69f9053..004c196 100644
--- a/src/os/mac/macho/Thread.go
+++ b/src/os/mac/macho/Thread.go
@@ -1,8 +1,11 @@
 package macho
 
+const ThreadSize = 184
+
 // Thread is a thread state load command.
 type Thread struct {
 	LoadCommand
 	Len  uint32
 	Type uint32
+	Data [43]uint32
 }