diff --git a/tools/mfc/card_only/staticnested_2x1nt_rf08s.c b/tools/mfc/card_only/staticnested_2x1nt_rf08s.c
index 2dd6ace23..10f31875d 100644
--- a/tools/mfc/card_only/staticnested_2x1nt_rf08s.c
+++ b/tools/mfc/card_only/staticnested_2x1nt_rf08s.c
@@ -223,7 +223,7 @@ int main(int argc, char *const argv[]) {
 
     char filter_filename2[40];
     uint32_t filter_keycount2 = 0;
-    snprintf(filter_filename2, sizeof(filter_filename2), "keys_%08x_%02iu_%08x_filtered.dic", uid2, sector2, nt2);
+    snprintf(filter_filename2, sizeof(filter_filename2), "keys_%08x_%02u_%08x_filtered.dic", uid2, sector2, nt2);
 
     fptr = fopen(filter_filename2, "w");
     if (fptr != NULL) {