diff --git a/src/iothread.cpp b/src/iothread.cpp
index 21017fbe7..9e252260b 100644
--- a/src/iothread.cpp
+++ b/src/iothread.cpp
@@ -14,6 +14,7 @@
 
 #include <atomic>
 #include <condition_variable>
+#include <cstdint> // for uint64_t
 #include <functional>
 #include <queue>