diff --git a/hash.c b/hash.c
index d8b301d94..fb81e4786 100644
--- a/hash.c
+++ b/hash.c
@@ -26,7 +26,9 @@ crypto_hash_sha512(unsigned char *out, const unsigned char *in,
 }
 
 #else
-#include <sha2.h>
+# ifdef HAVE_SHA2_H
+#  include <sha2.h>
+# endif
 
 int
 crypto_hash_sha512(unsigned char *out, const unsigned char *in,