Wrap <stdint.h> in #ifdef HAVE_STDINT_H.
diff --git a/xmss_commons.h b/xmss_commons.h
index 2cb7cc5..d9a920c 100644
--- a/xmss_commons.h
+++ b/xmss_commons.h
@@ -8,7 +8,9 @@
 #define XMSS_COMMONS_H
 
 #include <stdlib.h>
+#ifdef HAVE_STDINT_H
 #include <stdint.h>
+#endif
 
 void to_byte(unsigned char *output, unsigned long long in, uint32_t bytes);
 #if 0