diff --git a/include/haproxy/sc_strm.h b/include/haproxy/sc_strm.h
index 37460703f..3e2bea0bd 100644
--- a/include/haproxy/sc_strm.h
+++ b/include/haproxy/sc_strm.h
@@ -395,7 +395,19 @@ static inline int sc_is_send_allowed(const struct stconn *sc)
 	if (sc->flags & SC_FL_SHUT_DONE)
 		return 0;
 
-	return !sc_ep_test(sc, SE_FL_WAIT_DATA | SE_FL_WONT_CONSUME);
+	if (!sc_appctx(sc) || !(__sc_appctx(sc)->flags & APPCTX_FL_INOUT_BUFS))
+		return !sc_ep_test(sc, SE_FL_WAIT_DATA | SE_FL_WONT_CONSUME);
+
+	if (sc_ep_test(sc, SE_FL_WONT_CONSUME))
+		return 0;
+
+	if (sc_ep_test(sc, SE_FL_WAIT_DATA)) {
+		if (__sc_appctx(sc)->flags & (APPCTX_FL_INBLK_FULL|APPCTX_FL_INBLK_ALLOC))
+			return 0;
+		if (!co_data(sc_oc(sc)))
+			return 0;
+	}
+	return 1;
 }
 
 static inline int sc_rcv_may_expire(const struct stconn *sc)