diff --git a/ssl/dtls1.h b/ssl/dtls1.h
index 189acedfa..5d8ec71c3 100644
--- a/ssl/dtls1.h
+++ b/ssl/dtls1.h
@@ -62,6 +62,9 @@
 
 #include <openssl/buffer.h>
 #include <openssl/pqueue.h>
+#ifdef OPENSSL_SYS_WIN32
+/* Needed for struct timeval */
+#include <winsock.h>
 
 #ifdef  __cplusplus
 extern "C" {