diff --git a/lex.go b/lex.go
index 7542a6e..f4da2c0 100644
--- a/lex.go
+++ b/lex.go
@@ -41,8 +41,8 @@ func (t tokenType) String() string {
 		return "t_object_separator"
 	case t_object_end:
 		return "t_object_end"
-	case t_int:
-		return "t_int"
+	case t_number:
+		return "t_number"
 	default:
 		panic(fmt.Sprintf("unknown token type: %v", t))
 	}
@@ -62,7 +62,7 @@ const (
 	t_object_start                      // {
 	t_object_end                        // }
 	t_object_separator                  // :
-	t_int                               // an integer
+	t_number                            // a number
 )
 
 type stateFn func(*lexer) stateFn
@@ -72,6 +72,10 @@ type token struct {
 	s string
 }
 
+func (t token) String() string {
+	return fmt.Sprintf("{%s %s}", t.t, t.s)
+}
+
 type lexer struct {
 	in     io.RuneReader
 	out    chan token
@@ -125,6 +129,25 @@ func (l *lexer) emit(t tokenType) {
 	l.buf = l.buf[0:0]
 }
 
+func (l *lexer) accept(chars string) bool {
+	r := l.next()
+	if strings.IndexRune(chars, r) >= 0 {
+		l.keep(r)
+		return true
+	} else {
+		l.unread(r)
+		return false
+	}
+}
+
+func (l *lexer) acceptRun(chars string) bool {
+	none := true
+	for l.accept(chars) {
+		none = false
+	}
+	return !none
+}
+
 func lexString(in string) chan token {
 	r := strings.NewReader(in)
 	return lex(r)
@@ -195,9 +218,9 @@ func lexRoot(l *lexer) stateFn {
 		l.keep(r)
 		l.emit(t_object_separator)
 		return lexRoot
-	// case strings.IndexRune("-0123456789", r) >= 0:
-	// 	l.unread(r)
-	// 	return lexNumber, nil
+	case strings.IndexRune(".+-0123456789", r) >= 0:
+		l.unread(r)
+		return lexNumber
 	case unicode.IsSpace(r):
 		return lexRoot
 	case unicode.IsLower(r):
@@ -280,76 +303,34 @@ func lexType(l *lexer) stateFn {
 	}
 }
 
-// func lexNumber(l *lexer) (stateFn, error) {
-// 	r, err := l.next()
-// 	if err != nil {
-// 		return nil, err
-// 	}
-//
-// 	switch {
-// 	case r == '-', r == '+':
-// 		l.keep(r)
-// 		return lexNumber, nil
-// 	case r == '0':
-// 		l.keep(r)
-// 		return lexHexOct, nil
-// 	case strings.IndexRune("123456789", r) >= 0:
-// 		l.keep(r)
-// 		return lexDecimal, nil
-// 	default:
-// 		return nil, fmt.Errorf("unexpected rune in lexNumber: %c", r)
-// 	}
-// }
-//
-// func lexHexOct(l *lexer) (stateFn, error) {
-// 	r, err := l.next()
-// 	if err != nil {
-// 		return nil, err
-// 	}
-//
-// 	switch {
-// 	case r == 'x', r == 'X':
-// 		l.keep(r)
-// 		return lexHex, nil
-//     case r == 'e', r == 'E':
-//         l.keep(r)
-//         return lexExponent, nil
-// 	case r == '8', r == '9':
-// 		return nil, fmt.Errorf("unexpected 8 or 9 in lexHexOct.  there's no 8 or 9 in octal!")
-// 	case strings.IndexRune("01234567", r) >= 0:
-// 		l.keep(r)
-// 		return lexOct, nil
-// 	default:
-//         // we get here for the literals -0, +0 and 0
-// 		l.unread(r)
-//         l.emit(t_int)
-//         return lexRoot, nil
-// 	}
-// }
-//
-// func lexHex(l *lexer) (stateFn, error) {
-// 	r, err := l.next()
-// 	if err != nil {
-// 		return nil, err
-// 	}
-//
-//     switch {
-//
-//     }
-// }
-//
-// func lexDecimal(l *lexer) (stateFn, error) {
-// 	r, err := l.next()
-// 	if err != nil {
-// 		return nil, err
-// 	}
-//
-// 	switch {
-//     case strings.IndexRune("0123456789", r) >= 0:
-//         l.keep(r)
-//         return lexDecimal, nil
-//     case r == '.':
-//         l.keep(r)
-//         return lexFloat, nil
-// 	}
-// }
+func lexNumber(l *lexer) stateFn {
+	l.accept("+-")
+	digits := "0123456789"
+	if l.accept("0") {
+		if l.accept("xX") {
+			digits = "0123456789abcdefABCDEF"
+		} else {
+			digits = "01234567"
+		}
+	}
+	l.acceptRun(digits)
+	if l.accept(".") {
+		l.acceptRun(digits)
+	}
+	if l.accept("eE") {
+		l.accept("+-")
+		l.acceptRun("0123456789")
+	}
+	l.accept("i")
+	r := l.next()
+	if isAlphaNumeric(r) {
+		return lexErrorf("unexpected alphanum in lexNumber: %c", r)
+	}
+	l.unread(r)
+	l.emit(t_number)
+	return lexRoot
+}
+
+func isAlphaNumeric(r rune) bool {
+	return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
+}
diff --git a/lex_test.go b/lex_test.go
index 3ae07d0..19d65cf 100644
--- a/lex_test.go
+++ b/lex_test.go
@@ -49,6 +49,53 @@ var primitivesTests = []struct {
 		{t_string, "orelli"},
 		{t_object_end, "}"},
 	}},
+	{`{
+        first_name: "jordan",
+        last_name: "orelli",
+    }`, []token{
+		{t_object_start, "{"},
+		{t_name, "first_name"},
+		{t_object_separator, ":"},
+		{t_string, "jordan"},
+		{t_list_separator, ","},
+		{t_name, "last_name"},
+		{t_object_separator, ":"},
+		{t_string, "orelli"},
+		{t_list_separator, ","},
+		{t_object_end, "}"},
+	}},
+	{`0`, []token{{t_number, "0"}}},
+	{`-0`, []token{{t_number, "-0"}}},
+	{`+0`, []token{{t_number, "+0"}}},
+	{`+125`, []token{{t_number, "+125"}}},
+	{`-125`, []token{{t_number, "-125"}}},
+	{`.0`, []token{{t_number, ".0"}}},
+	{`15`, []token{{t_number, "15"}}},
+	{`0x0`, []token{{t_number, "0x0"}}},
+	{`0xa`, []token{{t_number, "0xa"}}},
+	{`0xc0dea5cf`, []token{{t_number, "0xc0dea5cf"}}},
+	{`12.345`, []token{{t_number, "12.345"}}},
+	{`12.345 name`, []token{{t_number, "12.345"}, {t_name, "name"}}},
+	{`[12.345]`, []token{
+		{t_list_start, "["},
+		{t_number, "12.345"},
+		{t_list_end, "]"},
+	}},
+	{`[1, 2, 3]`, []token{
+		{t_list_start, "["},
+		{t_number, "1"},
+		{t_list_separator, ","},
+		{t_number, "2"},
+		{t_list_separator, ","},
+		{t_number, "3"},
+		{t_list_end, "]"},
+	}},
+	// an imaginary number generates two lexemes; one for its real component,
+	// and one for its imaginary component.
+	{`1+2i`, []token{{t_number, "1"}, {t_number, "+2i"}}},
+	{`1e9`, []token{{t_number, "1e9"}}},
+	{`1e+9`, []token{{t_number, "1e+9"}}},
+	{`1E-9`, []token{{t_number, "1E-9"}}},
 }
 
 func TestLexPrimities(t *testing.T) {