diff --git a/lib/setopt.c b/lib/setopt.c
index a1666a4e03..e13bf2e372 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -906,7 +906,13 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
     arg = va_arg(param, unsigned long);
     if(arg > 1L)
       return CURLE_BAD_FUNCTION_ARGUMENT;
+#ifdef USE_HYPER
+    /* Hyper does not support HTTP/0.9 */
+    if(arg)
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+#else
     data->set.http09_allowed = arg ? TRUE : FALSE;
+#endif
     break;
 #endif   /* CURL_DISABLE_HTTP */