diff --git a/src/mbyte.c b/src/mbyte.c
index 7edab44..bf6fbb3 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -2320,7 +2320,7 @@
 		/* Single byte: first check normally, then with ignore case. */
 		if (s1[i] != s2[i])
 		{
-		    cdiff = TOLOWER_LOC(s1[i]) - TOLOWER_LOC(s2[i]);
+		    cdiff = MB_TOLOWER(s1[i]) - MB_TOLOWER(s2[i]);
 		    if (cdiff != 0)
 			return cdiff;
 		}