diff --git a/debugon.go b/debugon.go
index dcb8678..49039c8 100644
--- a/debugon.go
+++ b/debugon.go
@@ -74,10 +74,10 @@ func (dp *debugParser) logStart(ps *State) {
 func (dp *debugParser) logEnd(ps *State, result *Result) {
 	if log != nil {
 		if pendingOpenLog != "" {
-			fmt.Fprintf(log, dp.logf(ps, result, dp.Name()))
+			fmt.Fprint(log, dp.logf(ps, result, dp.Name()))
 			pendingOpenLog = ""
 		} else {
-			fmt.Fprintf(log, dp.logf(ps, result, "}"))
+			fmt.Fprint(log, dp.logf(ps, result, "}"))
 		}
 	}
 }
diff --git a/parser.go b/parser.go
index 489535c..f008d33 100644
--- a/parser.go
+++ b/parser.go
@@ -197,13 +197,13 @@ func parseMatcher(matcher string) (alphabet string, ranges [][]rune) {
 //  - min and max: Chars("a-z0-9", 4, 6) will match 4-6 lowercase alphanumeric characters
 // the above can be combined in any order
 func Chars(matcher string, repetition ...int) Parser {
-	return NewParser(fmt.Sprintf("Chars(%q)", matcher), charsImpl(matcher, false, repetition...))
+	return NewParser("["+matcher+"]", charsImpl(matcher, false, repetition...))
 }
 
 // NotChars accepts the full range of input from Chars, but it will stop when any
 // character matches. If you need to match until you see a sequence use Until instead
 func NotChars(matcher string, repetition ...int) Parser {
-	return NewParser(fmt.Sprintf("!Chars(%q)", matcher), charsImpl(matcher, true, repetition...))
+	return NewParser("!["+matcher+"]", charsImpl(matcher, true, repetition...))
 }
 
 func charsImpl(matcher string, stopOn bool, repetition ...int) Parser {