diff --git a/scanner/scanner.go b/scanner/scanner.go
index b5c3679..cf558e4 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -189,7 +189,12 @@ func (s *Scanner) Scan() token.Token {
 		case '+':
 			tok = token.ADD
 		case '-':
-			tok = token.SUB
+			if isDecimal(s.peek()) {
+				ch := s.next()
+				tok = s.scanNumber(ch)
+			} else {
+				tok = token.SUB
+			}
 		default:
 			s.err("illegal char")
 		}
diff --git a/scanner/scanner_test.go b/scanner/scanner_test.go
index 56ae526..6e2f7ab 100644
--- a/scanner/scanner_test.go
+++ b/scanner/scanner_test.go
@@ -52,7 +52,7 @@ var tokenLists = map[string][]tokenPair{
 		{token.BOOL, "true"},
 		{token.BOOL, "false"},
 	},
-	"identoken.t": []tokenPair{
+	"ident": []tokenPair{
 		{token.IDENT, "a"},
 		{token.IDENT, "a0"},
 		{token.IDENT, "foobar"},
@@ -70,7 +70,7 @@ var tokenLists = map[string][]tokenPair{
 		{token.IDENT, "foo६४"},
 		{token.IDENT, "bar９８７６"},
 	},
-	"stritoken.ng": []tokenPair{
+	"string": []tokenPair{
 		{token.STRING, `" "`},
 		{token.STRING, `"a"`},
 		{token.STRING, `"本"`},
@@ -92,7 +92,7 @@ var tokenLists = map[string][]tokenPair{
 		{token.STRING, `"\U0000ffAB"`},
 		{token.STRING, `"` + f100 + `"`},
 	},
-	"numbtoken.er": []tokenPair{
+	"number": []tokenPair{
 		{token.NUMBER, "0"},
 		{token.NUMBER, "1"},
 		{token.NUMBER, "9"},
@@ -131,8 +131,46 @@ var tokenLists = map[string][]tokenPair{
 		{token.NUMBER, "1E-10"},
 		{token.NUMBER, "42E+10"},
 		{token.NUMBER, "01234567890E-10"},
+		{token.NUMBER, "-0"},
+		{token.NUMBER, "-1"},
+		{token.NUMBER, "-9"},
+		{token.NUMBER, "-42"},
+		{token.NUMBER, "-1234567890"},
+		{token.NUMBER, "-00"},
+		{token.NUMBER, "-01"},
+		{token.NUMBER, "-07"},
+		{token.NUMBER, "-042"},
+		{token.NUMBER, "-01234567"},
+		{token.NUMBER, "-0x0"},
+		{token.NUMBER, "-0x1"},
+		{token.NUMBER, "-0xf"},
+		{token.NUMBER, "-0x42"},
+		{token.NUMBER, "-0x123456789abcDEF"},
+		{token.NUMBER, "-0x" + f100},
+		{token.NUMBER, "-0X0"},
+		{token.NUMBER, "-0X1"},
+		{token.NUMBER, "-0XF"},
+		{token.NUMBER, "-0X42"},
+		{token.NUMBER, "-0X123456789abcDEF"},
+		{token.NUMBER, "-0X" + f100},
+		{token.NUMBER, "-0e0"},
+		{token.NUMBER, "-1e0"},
+		{token.NUMBER, "-42e0"},
+		{token.NUMBER, "-01234567890e0"},
+		{token.NUMBER, "-0E0"},
+		{token.NUMBER, "-1E0"},
+		{token.NUMBER, "-42E0"},
+		{token.NUMBER, "-01234567890E0"},
+		{token.NUMBER, "-0e+10"},
+		{token.NUMBER, "-1e-10"},
+		{token.NUMBER, "-42e+10"},
+		{token.NUMBER, "-01234567890e-10"},
+		{token.NUMBER, "-0E+10"},
+		{token.NUMBER, "-1E-10"},
+		{token.NUMBER, "-42E+10"},
+		{token.NUMBER, "-01234567890E-10"},
 	},
-	"floatoken.t": []tokenPair{
+	"float": []tokenPair{
 		{token.FLOAT, "0."},
 		{token.FLOAT, "1."},
 		{token.FLOAT, "42."},
@@ -161,6 +199,26 @@ var tokenLists = map[string][]tokenPair{
 		{token.FLOAT, "1.1E-10"},
 		{token.FLOAT, "42.1E+10"},
 		{token.FLOAT, "01234567890.1E-10"},
+		{token.FLOAT, "-0.0"},
+		{token.FLOAT, "-1.0"},
+		{token.FLOAT, "-42.0"},
+		{token.FLOAT, "-01234567890.0"},
+		{token.FLOAT, "-01.8e0"},
+		{token.FLOAT, "-1.4e0"},
+		{token.FLOAT, "-42.2e0"},
+		{token.FLOAT, "-01234567890.12e0"},
+		{token.FLOAT, "-0.E0"},
+		{token.FLOAT, "-1.12E0"},
+		{token.FLOAT, "-42.123E0"},
+		{token.FLOAT, "-01234567890.213E0"},
+		{token.FLOAT, "-0.2e+10"},
+		{token.FLOAT, "-1.2e-10"},
+		{token.FLOAT, "-42.54e+10"},
+		{token.FLOAT, "-01234567890.98e-10"},
+		{token.FLOAT, "-0.1E+10"},
+		{token.FLOAT, "-1.1E-10"},
+		{token.FLOAT, "-42.1E+10"},
+		{token.FLOAT, "-01234567890.1E-10"},
 	},
 }