diff -Nrup a/ext/yahttp/yahttp/reqresp.cpp b/ext/yahttp/yahttp/reqresp.cpp
--- a/ext/yahttp/yahttp/reqresp.cpp	2019-02-07 12:24:13.000000000 -0700
+++ b/ext/yahttp/yahttp/reqresp.cpp	2019-11-06 19:40:29.039325844 -0700
@@ -2,6 +2,8 @@
 
 namespace YaHTTP {
 
+  template class AsyncLoader<Request>;
+
   bool isspace(char c) {
     return std::isspace(c) != 0;
   }