diff --git a/README.md b/README.md
index f9faea8233b5187184284aabe9f979f4281e41b7..2059c2d2d1314b518c664105285d42b5ec35346a 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,11 @@ services=""
 </pre>
 
 ### proxy_idp_auth_test.sh
+* Requirements:
+    * library *bc* 
+        <pre>
+        apt-get install bc
+        </pre>
 * Attributes to be filled:
 <pre>
 # The url of tested SP