diff --git a/fuzz/fuzzer.h b/fuzz/fuzzer.h
index 4d8b7b9a51..76eda2ce5d 100644
--- a/fuzz/fuzzer.h
+++ b/fuzz/fuzzer.h
@@ -8,8 +8,8 @@
  * or in the file LICENSE in the source distribution.
  */
 
-#include <stdint.h>     /* for uint8_t */
-#include <stddef.h>     /* for size_t */
+#include <stddef.h>              /* for size_t */
+#include <openssl/e_os2.h>       /* for uint8_t */
 
 int FuzzerTestOneInput(const uint8_t *buf, size_t len);
 int FuzzerInitialize(int *argc, char ***argv);