diff --git a/test/fuzzing/hb-subset-fuzzer.cc b/test/fuzzing/hb-subset-fuzzer.cc
index 863c495f419017ea0cbb00d96a7b277028e89cec..1e26d26a9c3537d0cba2c933ef581b3862c5e68a 100644
--- a/test/fuzzing/hb-subset-fuzzer.cc
+++ b/test/fuzzing/hb-subset-fuzzer.cc
@@ -8,7 +8,7 @@
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
-  printf ("hb-subset-fuzzer: input size = %d\n", size);
+  printf ("hb-subset-fuzzer: input size = %zu\n", size);
   hb_blob_t *blob = hb_blob_create ((const char *)data, size,
                                     HB_MEMORY_MODE_READONLY, NULL, NULL);
   hb_face_t *face = hb_face_create (blob, 0);