diff --git a/Makefile b/Makefile
index 33a1b33..c35170d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,6 @@
 .DEFAULT_GOAL := help
 
+PKGS := $(shell go list ./...)
 SOURCES := $(shell find . -path ./vendor -prune -o -name "*.go" -not -name '*_test.go' -print)
 
 .PHONY: setup
@@ -16,9 +17,8 @@ fmt: $(SOURCES) ## Formatting source codes.
 
 .PHONY: lint
 lint: ## Run golint and go vet.
-	@golint .
-	@golint -set_exit_status=1
-	@go vet .
+	@golint -set_exit_status=1 $(PKGS)
+	@go vet $(PKGS)
 
 .PHONY: test
 test:  ## Run tests with race condition checking.
diff --git a/completer/file.go b/completer/file.go
index 46c60a7..8da5251 100644
--- a/completer/file.go
+++ b/completer/file.go
@@ -12,6 +12,7 @@ import (
 )
 
 var (
+	// FilePathCompletionSeparator holds separate characters.
 	FilePathCompletionSeparator = string([]byte{' ', os.PathSeparator})
 )
 
diff --git a/internal/strings/strings.go b/internal/strings/strings.go
index c537876..f7d1886 100644
--- a/internal/strings/strings.go
+++ b/internal/strings/strings.go
@@ -2,9 +2,7 @@ package strings
 
 import "unicode/utf8"
 
-// IndexNotByte is similar with strings.IndexByte but returns
-// the index of the first instance of character except c in s.
-// or -1 if s only contains c.
+// IndexNotByte is similar with strings.IndexByte but showing the opposite behavior.
 func IndexNotByte(s string, c byte) int {
 	n := len(s)
 	for i := 0; i < n; i++ {
@@ -15,9 +13,7 @@ func IndexNotByte(s string, c byte) int {
 	return -1
 }
 
-// LastIndexByte is similar with strings.IndexByte but returns
-// the index of the last instance of character except c in s,
-// or -1 if s only contains c.
+// LastIndexNotByte is similar with strings.LastIndexByte but showing the opposite behavior.
 func LastIndexNotByte(s string, c byte) int {
 	for i := len(s) - 1; i >= 0; i-- {
 		if s[i] != c {
@@ -44,9 +40,7 @@ func makeASCIISet(chars string) (as asciiSet, ok bool) {
 	return as, true
 }
 
-// IndexNotAny is similar with strings.IndexAny but returns
-// the index of the first instance of any Unicode code point from chars in s,
-// or -1 if no Unicode code point from chars is present in s.
+// IndexNotAny is similar with strings.IndexAny but showing the opposite behavior.
 func IndexNotAny(s, chars string) int {
 	if len(chars) > 0 {
 		if len(s) > 8 {
@@ -76,9 +70,7 @@ func IndexNotAny(s, chars string) int {
 	return -1
 }
 
-// LastIndexAny returns the index of the last instance of any Unicode code
-// point from chars in s, or -1 if no Unicode code point from chars is
-// present in s.
+// LastIndexNotAny is similar with strings.LastIndexAny but showing the opposite behavior.
 func LastIndexNotAny(s, chars string) int {
 	if len(chars) > 0 {
 		if len(s) > 8 {