diff --git a/ch1-basic/ch1-03-array-string-and-slice.md b/ch1-basic/ch1-03-array-string-and-slice.md
index a940da6..0e20348 100644
--- a/ch1-basic/ch1-03-array-string-and-slice.md
+++ b/ch1-basic/ch1-03-array-string-and-slice.md
@@ -270,7 +270,7 @@ func forOnString(s string, forBody func(i int, r rune)) {
 	for i := 0; len(s) > 0; {
     	r, size := utf8.DecodeRuneInString(s)
 		forBody(i, r)
-    	s = s[size:]
+		s = s[size:]
 		i += size
 	}
 }