diff --git a/interface/wx/socket.h b/interface/wx/socket.h
index 0de0c81e43..36ad0f87d2 100644
--- a/interface/wx/socket.h
+++ b/interface/wx/socket.h
@@ -289,6 +289,12 @@ public:
     /**
         Constructor.
 
+        Notice that if the object is created from a worker thread or if it is
+        created from the main thread but the event loop is not running, @a
+        flags parameter @em must include ::wxSOCKET_BLOCK as non-blocking
+        sockets require dispatching events, which can only be done in the main
+        thread.
+
         @param flags
             Socket flags (See wxSocketBase::SetFlags())
     */
diff --git a/src/common/socket.cpp b/src/common/socket.cpp
index 37cd53783a..5fb8c291ae 100644
--- a/src/common/socket.cpp
+++ b/src/common/socket.cpp
@@ -25,7 +25,6 @@
 #include "wx/socket.h"
 
 #ifndef WX_PRECOMP
-    #include "wx/app.h"
     #include "wx/object.h"
     #include "wx/string.h"
     #include "wx/intl.h"
@@ -1975,6 +1974,15 @@ bool wxSocketBase::SetLocal(const wxIPV4address& local)
 wxSocketClient::wxSocketClient(wxSocketFlags flags)
               : wxSocketBase(flags, wxSOCKET_CLIENT)
 {
+    // Notice that we don't check for a running event loop here, unlike in
+    // GetBlockingFlagIfNeeded() because it is common to create the sockets
+    // before the event loop is entered and we shouldn't break existing code
+    // doing this as it can still work correctly if it only uses non-blocking
+    // sockets once the event loop is running.
+    wxASSERT_MSG( (flags & wxSOCKET_BLOCK) || wxIsMainThread(),
+                  wxS("Non-blocking sockets may only be created ")
+                  wxS("in the main thread") );
+
     m_initialRecvBufferSize =
     m_initialSendBufferSize = -1;
 }