diff --git a/ipv4/control_stub.go b/ipv4/control_stub.go
index f626de6d..4d850719 100644
--- a/ipv4/control_stub.go
+++ b/ipv4/control_stub.go
@@ -7,21 +7,17 @@
 package ipv4
 
 func setControlMessage(fd int, opt *rawOpt, cf ControlFlags, on bool) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func newControlMessage(opt *rawOpt) []byte {
-	// TODO(mikio): Implement this
 	return nil
 }
 
 func parseControlMessage(b []byte) (*ControlMessage, error) {
-	// TODO(mikio): Implement this
 	return nil, errOpNoSupport
 }
 
 func marshalControlMessage(cm *ControlMessage) []byte {
-	// TODO(mikio): Implement this
 	return nil
 }
diff --git a/ipv4/control_windows.go b/ipv4/control_windows.go
index 5a68a55a..800f6377 100644
--- a/ipv4/control_windows.go
+++ b/ipv4/control_windows.go
@@ -7,21 +7,21 @@ package ipv4
 import "syscall"
 
 func setControlMessage(fd syscall.Handle, opt *rawOpt, cf ControlFlags, on bool) error {
-	// TODO(mikio): Implement this
+	// TODO(mikio): implement this
 	return syscall.EWINDOWS
 }
 
 func newControlMessage(opt *rawOpt) []byte {
-	// TODO(mikio): Implement this
+	// TODO(mikio): implement this
 	return nil
 }
 
 func parseControlMessage(b []byte) (*ControlMessage, error) {
-	// TODO(mikio): Implement this
+	// TODO(mikio): implement this
 	return nil, syscall.EWINDOWS
 }
 
 func marshalControlMessage(cm *ControlMessage) []byte {
-	// TODO(mikio): Implement this
+	// TODO(mikio): implement this
 	return nil
 }
diff --git a/ipv4/dgramopt_stub.go b/ipv4/dgramopt_stub.go
index bee9e040..a4688d92 100644
--- a/ipv4/dgramopt_stub.go
+++ b/ipv4/dgramopt_stub.go
@@ -9,41 +9,33 @@ package ipv4
 import "net"
 
 func (c *dgramOpt) MulticastTTL() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *dgramOpt) SetMulticastTTL(ttl int) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func (c *dgramOpt) MulticastInterface() (*net.Interface, error) {
-	// TODO(mikio): Implement this
 	return nil, errOpNoSupport
 }
 
 func (c *dgramOpt) SetMulticastInterface(ifi *net.Interface) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func (c *dgramOpt) MulticastLoopback() (bool, error) {
-	// TODO(mikio): Implement this
 	return false, errOpNoSupport
 }
 
 func (c *dgramOpt) SetMulticastLoopback(on bool) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func (c *dgramOpt) JoinGroup(ifi *net.Interface, grp net.Addr) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func (c *dgramOpt) LeaveGroup(ifi *net.Interface, grp net.Addr) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
diff --git a/ipv4/genericopt_stub.go b/ipv4/genericopt_stub.go
index b202744d..93192b39 100644
--- a/ipv4/genericopt_stub.go
+++ b/ipv4/genericopt_stub.go
@@ -7,21 +7,17 @@
 package ipv4
 
 func (c *genericOpt) TOS() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *genericOpt) SetTOS(tos int) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
 
 func (c *genericOpt) TTL() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *genericOpt) SetTTL(ttl int) error {
-	// TODO(mikio): Implement this
 	return errOpNoSupport
 }
diff --git a/ipv4/header.go b/ipv4/header.go
index 672f2d34..58b131c4 100644
--- a/ipv4/header.go
+++ b/ipv4/header.go
@@ -100,6 +100,7 @@ func (h *Header) Marshal() ([]byte, error) {
 		b[posTotalLen], b[posTotalLen+1] = byte(h.TotalLen>>8), byte(h.TotalLen)
 		b[posFragOff], b[posFragOff+1] = byte(flagsAndFragOff>>8), byte(flagsAndFragOff)
 	} else {
+		// TODO(mikio): fix spurious word boundary access
 		*(*uint16)(unsafe.Pointer(&b[posTotalLen : posTotalLen+1][0])) = uint16(h.TotalLen)
 		*(*uint16)(unsafe.Pointer(&b[posFragOff : posFragOff+1][0])) = uint16(flagsAndFragOff)
 	}
@@ -141,10 +142,12 @@ func ParseHeader(b []byte) (*Header, error) {
 		h.TotalLen = int(b[posTotalLen])<<8 | int(b[posTotalLen+1])
 		h.FragOff = int(b[posFragOff])<<8 | int(b[posFragOff+1])
 	} else {
+		// TODO(mikio): fix spurious word boundary access
 		h.TotalLen = int(*(*uint16)(unsafe.Pointer(&b[posTotalLen : posTotalLen+1][0])))
 		if runtime.GOOS != "freebsd" || freebsdVersion < 1000000 {
 			h.TotalLen += hdrlen
 		}
+		// TODO(mikio): fix spurious word boundary access
 		h.FragOff = int(*(*uint16)(unsafe.Pointer(&b[posFragOff : posFragOff+1][0])))
 	}
 	h.Flags = HeaderFlags(h.FragOff&0xe000) >> 13
diff --git a/ipv4/helper_stub.go b/ipv4/helper_stub.go
index 314d4d5f..dc2120cf 100644
--- a/ipv4/helper_stub.go
+++ b/ipv4/helper_stub.go
@@ -7,21 +7,17 @@
 package ipv4
 
 func (c *genericOpt) sysfd() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *dgramOpt) sysfd() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *payloadHandler) sysfd() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }
 
 func (c *packetHandler) sysfd() (int, error) {
-	// TODO(mikio): Implement this
 	return 0, errOpNoSupport
 }