diff --git a/lib/lex.go b/lib/lex.go
index baa1d01..fdf2f6e 100644
--- a/lib/lex.go
+++ b/lib/lex.go
@@ -17,8 +17,8 @@ func init() {
 
 // LexRoot is the root lex implementation
 func LexRoot(s *State) (LexType, error) {
-	if s.buff != nil {
-		return nil, s.errorUnknown("incomplete buffer: %s", string(s.buff))
+	if s.buffer != nil {
+		return nil, s.errorUnknown("incomplete buffer: %s", string(s.buffer))
 	}
 	if s.end() {
 		if s.openParenth > 0 {
@@ -83,13 +83,13 @@ func lexBackslash(s *State) (LexType, error) {
 	s.move(1)
 	switch c {
 	case 'u':
-		if s.buff != nil {
-			return nil, s.errorUnknown("incomplete buffer: %s", string(s.buff))
+		if s.buffer != nil {
+			return nil, s.errorUnknown("incomplete buffer: %s", string(s.buffer))
 		}
 		return lexRootUnicode, nil
 	case 'U':
-		if s.buff != nil {
-			return nil, s.errorUnknown("incomplete buffer: %s", string(s.buff))
+		if s.buffer != nil {
+			return nil, s.errorUnknown("incomplete buffer: %s", string(s.buffer))
 		}
 		return lexRootUnicodeWide, nil
 	}
@@ -114,28 +114,28 @@ func lexIdent(s *State) (LexType, error) {
 		s.openParenth++
 		return lexIdentFuncCall, nil
 	}
-	s.buff = append(s.buff, c)
+	s.buffer = append(s.buffer, c)
 	return lexIdent, nil
 }
 
-func makeLexUnicode(parentLex LexType, symbol rune, width int, toBuff bool) LexType {
+func makeLexUnicode(parentLex LexType, symbol rune, width int, toBuffer bool) LexType {
 	return func(s *State) (LexType, error) {
-		buff := make([]rune, 0, width)
-		buff = append(buff, '\\', symbol)
-		for ; len(buff) < width && !s.end(); s.move(1) {
-			buff = append(buff, s.input[s.inputPos])
+		buffer := make([]rune, 0, width)
+		buffer = append(buffer, '\\', symbol)
+		for ; len(buffer) < width && !s.end(); s.move(1) {
+			buffer = append(buffer, s.input[s.inputPos])
 		}
-		if len(buff) != width {
-			s.errorMarkLen = len(buff)
+		if len(buffer) != width {
+			s.errorMarkLen = len(buffer)
 			return nil, s.errorSyntax("invalid escape sequence")
 		}
-		char, _, _, err := strconv.UnquoteChar(string(buff), '"')
+		char, _, _, err := strconv.UnquoteChar(string(buffer), '"')
 		if err != nil {
 			s.errorMarkLen = width
 			return nil, s.errorSyntax("invalid escape sequence")
 		}
-		if toBuff {
-			s.buff = append(s.buff, char)
+		if toBuffer {
+			s.buffer = append(s.buffer, char)
 		} else {
 			err := s.addOutputOne(char)
 			if err != nil {
diff --git a/lib/lex_charclass.go b/lib/lex_charclass.go
index f8d5764..cf6bb20 100644
--- a/lib/lex_charclass.go
+++ b/lib/lex_charclass.go
@@ -15,7 +15,7 @@ func processRange(s *State, charset []rune) (LexType, error) {
 	if err != nil {
 		return nil, err
 	}
-	s.buff = nil
+	s.buffer = nil
 	s.lastGen = gen
 	return LexRoot, nil
 }
@@ -37,14 +37,14 @@ func lexRange(s *State) (LexType, error) {
 	case '-':
 		return lexRangeDashInit, nil
 	case '^':
-		if !s.rangeReverse && len(s.buff) == 0 {
+		if !s.rangeReverse && len(s.buffer) == 0 {
 			s.rangeReverse = true
 			return lexRange, nil
 		}
 	case ']':
-		return processRange(s, s.buff)
+		return processRange(s, s.buffer)
 	}
-	s.buff = append(s.buff, c)
+	s.buffer = append(s.buffer, c)
 	return lexRange, nil
 }
 
@@ -65,7 +65,7 @@ func lexRangeColon(s *State) (LexType, error) {
 				s.errorMarkLen = len(name) + 2
 				return nil, s.errorValue("invalid character class %#v", name)
 			}
-			s.buff = append(s.buff, charset...)
+			s.buffer = append(s.buffer, charset...)
 			return lexRange, nil
 		case ']':
 			s.errorMarkLen = len(nameRunes) + 2
@@ -81,10 +81,10 @@ func lexRangeColon(s *State) (LexType, error) {
 func lexRangeDashInit(s *State) (LexType, error) {
 	if s.end() {
 		s.errorOffset++
-		s.errorMarkLen = len(s.buff) + 3
+		s.errorMarkLen = len(s.buffer) + 3
 		return nil, s.errorSyntax("'[' not closed")
 	}
-	s.buff = append(s.buff, s.input[s.inputPos-1], s.input[s.inputPos])
+	s.buffer = append(s.buffer, s.input[s.inputPos-1], s.input[s.inputPos])
 	s.move(1)
 	if s.end() {
 		return nil, s.errorSyntax("no character after '-'")
@@ -93,23 +93,23 @@ func lexRangeDashInit(s *State) (LexType, error) {
 }
 
 func lexRangeDash(s *State) (LexType, error) {
-	n := len(s.buff)
+	n := len(s.buffer)
 	if n < 3 {
 		s.errorOffset--
 		return nil, s.errorSyntax("no character before '-'")
 	}
-	c1 := s.buff[n-1]
+	c1 := s.buffer[n-1]
 	if c1 == '\\' {
-		s.buff = s.buff[:n-1]
+		s.buffer = s.buffer[:n-1]
 		return lexRangeDashBackslash, nil
 	}
-	if s.buff[n-2] != '-' {
-		return nil, s.errorUnknown("expected '-', buffer=%#v", string(s.buff))
+	if s.buffer[n-2] != '-' {
+		return nil, s.errorUnknown("expected '-', buffer=%#v", string(s.buffer))
 	}
-	c0 := s.buff[n-3]
-	s.buff = s.buff[:n-2]
+	c0 := s.buffer[n-3]
+	s.buffer = s.buffer[:n-2]
 	for b := int(c0) + 1; b <= int(c1); b++ {
-		s.buff = append(s.buff, rune(b))
+		s.buffer = append(s.buffer, rune(b))
 	}
 	return lexRange, nil
 }
@@ -126,7 +126,7 @@ func lexRangeBackslash(s *State) (LexType, error) {
 	if c == 'U' {
 		return makeLexUnicode(lexRange, 'U', 10, true), nil
 	}
-	s.buff = append(s.buff, backslashEscape(c))
+	s.buffer = append(s.buffer, backslashEscape(c))
 	return lexRange, nil
 }
 
@@ -142,6 +142,6 @@ func lexRangeDashBackslash(s *State) (LexType, error) {
 	if c == 'U' {
 		return makeLexUnicode(lexRangeDash, 'U', 10, true), nil
 	}
-	s.buff = append(s.buff, backslashEscape(c))
+	s.buffer = append(s.buffer, backslashEscape(c))
 	return lexRangeDash, nil
 }
diff --git a/lib/lex_function.go b/lib/lex_function.go
index 534376b..c2f85c5 100644
--- a/lib/lex_function.go
+++ b/lib/lex_function.go
@@ -1,6 +1,6 @@
 package passgen
 
-func _lexIdentFuncCallParanClose(s *State, buff []rune) (LexType, error) {
+func _lexIdentFuncCallParanClose(s *State, buffer []rune) (LexType, error) {
 	if s.openBracket {
 		return nil, nil
 	}
@@ -10,12 +10,12 @@ func _lexIdentFuncCallParanClose(s *State, buff []rune) (LexType, error) {
 	}
 	s.move(1)
 	s2 := NewState(s.SharedState.Copy(), s.input)
-	s2.errorOffset -= int64(len(buff) + 1)
-	funcName := string(s.buff)
+	s2.errorOffset -= int64(len(buffer) + 1)
+	funcName := string(s.buffer)
 	if funcName == "" {
 		return nil, s2.errorSyntax("missing function name")
 	}
-	gen, err := getFuncGenerator(s2, funcName, buff)
+	gen, err := getFuncGenerator(s2, funcName, buffer)
 	if err != nil {
 		return nil, err
 	}
@@ -26,7 +26,7 @@ func _lexIdentFuncCallParanClose(s *State, buff []rune) (LexType, error) {
 	s.output = append(s.output, s2.output...)
 	s.patternEntropy = s2.patternEntropy
 	s.lastGroupId = s2.lastGroupId
-	s.buff = nil
+	s.buffer = nil
 	s.lastGen = gen
 	return LexRoot, nil
 }
@@ -39,13 +39,13 @@ func _lexIdentFuncCallEndError(s *State) error {
 	return s.errorSyntax(s_func_call_expected)
 }
 
-func _lexIdentFuncCallBackslash(s *State, buff []rune) []rune {
-	buff = append(buff, '\\')
+func _lexIdentFuncCallBackslash(s *State, buffer []rune) []rune {
+	buffer = append(buffer, '\\')
 	s.move(1)
 	if !s.end() {
-		buff = append(buff, s.input[s.inputPos])
+		buffer = append(buffer, s.input[s.inputPos])
 	}
-	return buff
+	return buffer
 }
 
 func lexIdentFuncCall(s *State) (LexType, error) {
diff --git a/lib/lex_group.go b/lib/lex_group.go
index d08bbe3..9e3c4f5 100644
--- a/lib/lex_group.go
+++ b/lib/lex_group.go
@@ -19,7 +19,7 @@ func lexGroup(s *State) (LexType, error) {
 	case ')':
 		s.openParenth--
 		if s.openParenth > 0 {
-			s.buff = append(s.buff, ')')
+			s.buffer = append(s.buffer, ')')
 			return lexGroup, nil
 		}
 		return processGroupEnd(s)
@@ -28,10 +28,10 @@ func lexGroup(s *State) (LexType, error) {
 			s.errorOffset++
 			return nil, s.errorSyntax("'|' at the end of group")
 		}
-		s.moveBack(uint64(len(s.buff) + 1))
+		s.moveBack(uint64(len(s.buffer) + 1))
 		return lexGroupAlter, nil
 	}
-	s.buff = append(s.buff, c)
+	s.buffer = append(s.buffer, c)
 	return lexGroup, nil
 }
 
@@ -82,7 +82,7 @@ Loop:
 	s.move(1)
 	s.openParenth--
 	s.lastGen = gen
-	s.buff = nil
+	s.buffer = nil
 	return LexRoot, nil
 }
 
@@ -93,7 +93,7 @@ func processGroupBackslash(s *State) (LexType, error) {
 	}
 	c := s.input[s.inputPos]
 	s.move(1)
-	s.buff = append(s.buff, '\\', c)
+	s.buffer = append(s.buffer, '\\', c)
 	return lexGroup, nil
 }
 
@@ -102,8 +102,8 @@ func processGroupEnd(s *State) (LexType, error) {
 	lastOutputSize := len(s.output)
 	s2 := NewState(s.SharedState.Copy(), s.input)
 	s2.output = s.output
-	s2.errorOffset -= int64(len(s.buff) + 1)
-	gen := newGroupGenerator(s.buff)
+	s2.errorOffset -= int64(len(s.buffer) + 1)
+	gen := newGroupGenerator(s.buffer)
 	err := gen.Generate(s2)
 	if err != nil {
 		return nil, err
@@ -113,7 +113,7 @@ func processGroupEnd(s *State) (LexType, error) {
 	s.lastGroupId = s2.lastGroupId
 	s.groupsOutput[groupId] = s.output[lastOutputSize:]
 	s.lastGen = gen
-	s.buff = nil
+	s.buffer = nil
 	return LexRoot, nil
 }
 
diff --git a/lib/lex_repeat.go b/lib/lex_repeat.go
index 2f1b483..23ff604 100644
--- a/lib/lex_repeat.go
+++ b/lib/lex_repeat.go
@@ -22,28 +22,28 @@ func lexRepeat(s *State) (LexType, error) {
 	case '$':
 		return nil, s.errorSyntax("'$' inside {...}")
 	case ',':
-		if hasRune(s.buff, ',') {
+		if hasRune(s.buffer, ',') {
 			return nil, s.errorSyntax("multiple ',' inside {...}")
 		}
-		s.buff = append(s.buff, c)
+		s.buffer = append(s.buffer, c)
 		return lexRepeat, nil
 	case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
-		s.buff = append(s.buff, c)
+		s.buffer = append(s.buffer, c)
 		return lexRepeat, nil
 	case '-':
-		if hasRune(s.buff, ',') {
+		if hasRune(s.buffer, ',') {
 			return nil, s.errorSyntax("invalid natural number")
 		}
 		return nil, s.errorSyntax("repetition range syntax is '{M,N}' not '{M-N}'")
 	case '}':
 		return closeLexRepeat(s)
 	}
-	s.errorMarkLen = len(s.buff) + 1
+	s.errorMarkLen = len(s.buffer) + 1
 	return nil, s.errorSyntax("invalid natural number inside {...}")
 }
 
 func closeLexRepeat(s *State) (LexType, error) {
-	if len(s.buff) == 0 {
+	if len(s.buffer) == 0 {
 		return nil, s.errorSyntax("missing number inside {}")
 	}
 	if s.lastGen == nil {
@@ -52,7 +52,7 @@ func closeLexRepeat(s *State) (LexType, error) {
 	}
 	child := s.lastGen
 	// FIXME: lastGen may have used another state
-	count, err := parseRepeatCount(s, s.buff)
+	count, err := parseRepeatCount(s, s.buffer)
 	if err != nil {
 		return nil, err
 	}
@@ -73,7 +73,7 @@ func closeLexRepeat(s *State) (LexType, error) {
 	// but we need to re-set g.count after gen.Generate(s), because the whole thing
 	// might be repeated again
 	s.lastGen = gen
-	s.buff = nil
+	s.buffer = nil
 	return LexRoot, nil
 }
 
diff --git a/lib/state.go b/lib/state.go
index 9c01f18..985ee2f 100644
--- a/lib/state.go
+++ b/lib/state.go
@@ -30,7 +30,7 @@ type State struct {
 	lastGen generatorIface
 
 	input  []rune
-	buff   []rune
+	buffer []rune
 	output []rune
 
 	inputPos uint64