diff --git a/misc.go b/misc.go
index 31a3cfb..f8a6953 100644
--- a/misc.go
+++ b/misc.go
@@ -24,7 +24,7 @@ func dotChars() []rune { // Returns all possible characters represented by the d
 // Returns true if str[idx] and str[idx-1] are separated by a word boundary.
 func isWordBoundary(str []rune, idx int) bool {
 	wbounded := idx == 0 ||
-		idx == len(str)-1 ||
+		idx >= len(str)-1 ||
 		(!slices.Contains(wordChars, str[idx-1]) && slices.Contains(wordChars, str[idx])) ||
 		(slices.Contains(wordChars, str[idx-1]) && !slices.Contains(wordChars, str[idx]))
 	return wbounded