diff --git a/intl/hyphenation/hyphen/hyphen.c b/intl/hyphenation/hyphen/hyphen.c
index 9f2b7112c8..bd7e9a790c 100644
--- a/intl/hyphenation/hyphen/hyphen.c
+++ b/intl/hyphenation/hyphen/hyphen.c
@@ -446,7 +446,7 @@ for (k = 0; k < 2; k++) {
         while ((c = fgetc(f)) != '\n' && c != EOF);
         /* issue warning if not a comment */
         if (buf[0] != '%') {
-          fprintf(stderr, "Warning: skipping too long pattern (more than %lu chars)\n", sizeof(buf));
+          fprintf(stderr, "Warning: skipping too long pattern (more than %zu chars)\n", sizeof(buf));
         }
         continue;
       }