diff --git a/src/lib/util/astring.c b/src/lib/util/astring.c
index 1e7da3487b6..d6956121ef9 100644
--- a/src/lib/util/astring.c
+++ b/src/lib/util/astring.c
@@ -566,7 +566,7 @@ astring *astring_tolower(astring *str)
 {
 	char *text;
 
-	/* just toupper() on all characters */
+	/* just tolower() on all characters */
 	for (text = str->text; *text != 0; text++)
 		*text = tolower(*text);