diff --git a/targettest/strnlen.c b/targettest/strnlen.c
index d07b7628c..ac39f2396 100644
--- a/targettest/strnlen.c
+++ b/targettest/strnlen.c
@@ -8,7 +8,7 @@ void
 check (size_t result, size_t expected)
 {
     if (result != expected) {
-        printf ("Expected strnlen() to return %d, got %d.\n",
+        printf ("Expected strnlen() to return %u, got %u.\n",
                 expected, result);
         exit (EXIT_FAILURE);
     }