diff --git a/ixwebsocket/IXSocket.h b/ixwebsocket/IXSocket.h
index 2b981936..8084e219 100644
--- a/ixwebsocket/IXSocket.h
+++ b/ixwebsocket/IXSocket.h
@@ -9,6 +9,7 @@
 #include <string>
 #include <functional>
 #include <mutex>
+#include <atomic>
 
 namespace ix 
 {
diff --git a/ixwebsocket/IXWebSocketTransport.h b/ixwebsocket/IXWebSocketTransport.h
index ac7c39a1..1fc1f2e4 100644
--- a/ixwebsocket/IXWebSocketTransport.h
+++ b/ixwebsocket/IXWebSocketTransport.h
@@ -15,6 +15,7 @@
 #include <functional>
 #include <memory>
 #include <mutex>
+#include <atomic>
 
 namespace ix 
 {