diff --git a/lexer/lexer.go b/lexer/lexer.go
index 8d909ab..57cbbb7 100644
--- a/lexer/lexer.go
+++ b/lexer/lexer.go
@@ -58,114 +58,6 @@ func (lexer *LexingOperation) tokenize () (err error) {
 	return
 }
 
-// tokenizeSymbolBeginning lexes a token that starts with a number.
-func (lexer *LexingOperation) tokenizeNumberBeginning (negative bool) (err error) {
-	var number uint64
-
-	if lexer.char == '0' {
-		lexer.nextRune()
-
-		if lexer.char == 'x' {
-			lexer.nextRune()
-			number, err = lexer.tokenizeHexidecimalNumber()
-		} else if lexer.char == 'b' {
-			lexer.nextRune()
-			number, err = lexer.tokenizeBinaryNumber()
-		} else if lexer.char == '.' {
-			number, err = lexer.tokenizeDecimalNumber()
-		} else if lexer.char >= '0' && lexer.char <= '9' {
-			number, err = lexer.tokenizeOctalNumber()
-		} else {
-			return file.NewError (
-				lexer.file.Location(), 1,
-				"unexpected character in number literal",
-				file.ErrorKindError)
-		}
-	} else {
-		number, err = lexer.tokenizeDecimalNumber()
-	}
-
-	if err != nil { return }
-
-	token := Token { }
-
-	if negative {
-		token.kind  = TokenKindInt
-		token.value = int64(number) * -1
-	} else {
-		token.kind  = TokenKindUInt
-		token.value = uint64(number)
-	}
-	
-	lexer.addToken(token)
-	return
-}
-
-// tokenizeHexidecimalNumber Reads and tokenizes a hexidecimal number.
-func (lexer *LexingOperation) tokenizeHexidecimalNumber () (number uint64, err error) {
-	for {
-		if lexer.char >= '0' && lexer.char <= '9' {
-			number *= 16
-			number += uint64(lexer.char - '0')
-		} else if lexer.char >= 'A' && lexer.char <= 'F' {
-			number *= 16
-			number += uint64(lexer.char - 'A' + 9)
-		} else if lexer.char >= 'a' && lexer.char <= 'f' {
-			number *= 16
-			number += uint64(lexer.char - 'a' + 9)
-		} else {
-			break
-		}
-
-		err = lexer.nextRune()
-		if err != nil { return }
-	}
-	return
-}
-
-// tokenizeBinaryNumber Reads and tokenizes a binary number.
-func (lexer *LexingOperation) tokenizeBinaryNumber () (number uint64, err error) {
-	for {
-		if lexer.char == '0' {
-			number *= 2
-		} else if lexer.char == '1' {
-			number *= 2
-			number += 1
-		} else {
-			break
-		}
-
-		err = lexer.nextRune()
-		if err != nil { return }
-	}
-	return
-}
-
-// tokenizeDecimalNumber Reads and tokenizes a decimal number.
-func (lexer *LexingOperation) tokenizeDecimalNumber () (number uint64, err error) {
-	for lexer.char >= '0' && lexer.char <= '9' {
-		number *= 10
-		number += uint64(lexer.char - '0')
-		
-		err = lexer.nextRune()
-		if err != nil { return }
-	}
-	
-	return
-}
-
-// tokenizeOctalNumber Reads and tokenizes an octal number.
-func (lexer *LexingOperation) tokenizeOctalNumber () (number uint64, err error) {
-	for lexer.char >= '0' && lexer.char <= '7' {
-		number *= 8
-		number += uint64(lexer.char - '0')
-		
-		err = lexer.nextRune()
-		if err != nil { return }
-	}
-	return
-}
-
 func (lexer *LexingOperation) tokenizeAlphaBeginning () (err error) {
 	got := ""
 
diff --git a/lexer/numbers.go b/lexer/numbers.go
new file mode 100644
index 0000000..df1634d
--- /dev/null
+++ b/lexer/numbers.go
@@ -0,0 +1,127 @@
+package lexer
+
+import "github.com/sashakoshka/arf/file"
+
+// tokenizeSymbolBeginning lexes a token that starts with a number.
+func (lexer *LexingOperation) tokenizeNumberBeginning (negative bool) (err error) {
+	var number uint64
+
+	if lexer.char == '0' {
+		lexer.nextRune()
+
+		if lexer.char == 'x' {
+			lexer.nextRune()
+			number, err = lexer.tokenizeHexidecimalNumber()
+		} else if lexer.char == 'b' {
+			lexer.nextRune()
+			number, err = lexer.tokenizeBinaryNumber()
+		} else if lexer.char == '.' {
+			number, err = lexer.tokenizeDecimalNumber()
+		} else if lexer.char >= '0' && lexer.char <= '9' {
+			number, err = lexer.tokenizeOctalNumber()
+		} else {
+			return file.NewError (
+				lexer.file.Location(), 1,
+				"unexpected character in number literal",
+				file.ErrorKindError)
+		}
+	} else {
+		number, err = lexer.tokenizeDecimalNumber()
+	}
+
+	if err != nil { return }
+
+	token := Token { }
+
+	if negative {
+		token.kind  = TokenKindInt
+		token.value = int64(number) * -1
+	} else {
+		token.kind  = TokenKindUInt
+		token.value = uint64(number)
+	}
+	
+	lexer.addToken(token)
+	return
+}
+
+func runeToDigit (char rune, radix uint64) (digit uint64, worked bool) {
+	worked = true
+
+	if char >= '0' && char <= '9' {
+		digit = uint64(char - '0')
+	} else if char >= 'A' && char <= 'F' {
+		digit = uint64(char - 'A' + 9)
+	} else if char >= 'a' && char <= 'f' {
+		digit = uint64(char - 'a' + 9)
+	} else {
+		worked = false
+	}
+
+	if digit >= radix {
+		worked = false
+	}
+
+	return
+}
+
+// tokenizeHexidecimalNumber Reads and tokenizes a hexidecimal number.
+func (lexer *LexingOperation) tokenizeHexidecimalNumber () (number uint64, err error) {
+	for {
+		digit, worked := runeToDigit(lexer.char, 16)
+		if !worked { break }
+
+		number *= 16
+		number += digit
+
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+	return
+}
+
+// tokenizeBinaryNumber Reads and tokenizes a binary number.
+func (lexer *LexingOperation) tokenizeBinaryNumber () (number uint64, err error) {
+	for {
+		digit, worked := runeToDigit(lexer.char, 2)
+		if !worked { break }
+
+		number *= 2
+		number += digit
+
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+	return
+}
+
+// tokenizeDecimalNumber Reads and tokenizes a decimal number.
+func (lexer *LexingOperation) tokenizeDecimalNumber () (number uint64, err error) {
+	for {
+		digit, worked := runeToDigit(lexer.char, 10)
+		if !worked { break }
+
+		number *= 10
+		number += digit
+		
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+	
+	return
+}
+
+// tokenizeOctalNumber Reads and tokenizes an octal number.
+func (lexer *LexingOperation) tokenizeOctalNumber () (number uint64, err error) {
+	for {
+		digit, worked := runeToDigit(lexer.char, 8)
+		if !worked { break }
+
+		number *= 8
+		number += digit
+		
+		err = lexer.nextRune()
+		if err != nil { return }
+	}
+	return
+}