Added polymorphic_value to OSS users
diff --git a/docs/opensource-users.md b/docs/opensource-users.md
index e1f87e6..03ec331 100644
--- a/docs/opensource-users.md
+++ b/docs/opensource-users.md
@@ -37,6 +37,9 @@
### [SOCI](https://github.com/SOCI/soci)
The C++ Database Access Library
+### [polymorphic_value](https://github.com/jbcoe/polymorphic_value)
+A polymorphic value-type for C++
+
### [Ppconsul](https://github.com/oliora/ppconsul)
A C++ client library for Consul. Consul is a distributed tool for discovering and configuring services in your infrastructure