diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index 25b46a158..cfd1f8c58 100644
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -43,8 +43,13 @@ extern "C" {
 #define strcasecmp stricmp
 #define getdtablesize() 30000
 
+#ifndef __SSIZE_T
+#define __SSIZE_T
+
 typedef SSIZE_T ssize_t;
 
+#endif // __SSIZE_T
+
 #define LWS_VISIBLE
 
 #ifdef LWS_DLL