diff --git a/src/ext/siphash.h b/src/ext/siphash.h
index 730e49937d..0207a959ff 100644
--- a/src/ext/siphash.h
+++ b/src/ext/siphash.h
@@ -1,6 +1,8 @@
 #ifndef SIPHASH_H
 #define SIPHASH_H
 
+#include <stdint.h>
+
 struct sipkey {
   uint64_t k0;
   uint64_t k1;