diff --git a/README.md b/README.md
index c44e6af..dac61f4 100644
--- a/README.md
+++ b/README.md
@@ -1,18 +1,20 @@
 #reflex2q3
 Converts Reflex maps, both version 6 and 8, into id Tech's .map format. 
 
-###Building:
+####Requires
+* [Eigen 3, C++ template library](http://eigen.tuxfamily.org/index.php?title=Main_Page)
+
+####Building:
         git submodule update --init --recursive
         cd ReflexToQ3
         make
 
-###Minimum to convert map (geometry only): 
+####Minimum to convert map (geometry only): 
         ./reflex2q3 [input].map [output].map
 
-###View complete list of arguments:
+####View complete list of arguments:
         ./reflex2q3 --help
 
-
 ####Compiler(s)
 * mingw-w64, GCC 5.3.0