diff --git a/README.md b/README.md
index f83c38551c0c30484a42b86aebb74c926640b90b..399c24a7ccf3fa11e0b3ba377fc57b8ec4803ee5 100644
--- a/README.md
+++ b/README.md
@@ -8,3 +8,9 @@ FPGA code for Elphel 393 camera, created with [VDT plugin](https://github.com/El
 [Documentation](http://docs.elphel.com/x393) is generated with Doxygen-based Doxverilog.
 
 Run ./INIT_PROJECT in the top directory to copy initial .project and .pydevproject files for Eclipse
+
+Simulation of this project requires some files from the Xilinx proprietary _unisims_ library (list of dependencies
+is in this [blog post](http://blog.elphel.com/2016/03/free-fpga-reimplement-the-primitives-models/) ).
+[VDT plugin](https://github.com/Elphel/vdt-plugin) README file describes steps needed after installation of Xilinx software
+(unisims library is not distributed separatly). 
+