diff --git a/README b/README
index a1c5851a9..1429a88d4 100644
--- a/README
+++ b/README
@@ -32,3 +32,7 @@ As Skype requires that you accept its license, the plugin is not compiled and en
 - you compile the UI with HAVE_SILK preprocessor macro (xcode). 
 - you compile add libmssilk.so to the list a library (xcode).
 
+ZRTP
+liblinphone-sdk depends on the GNU LIBZRTPCPP extension for ZRTP support.
+As the license of this library is GPLv3+ it is not enabled unless the enable_zrtp=yes option is passed to the make command.
+Note that activiting ZRTP makes the license of the whole application GPLv3+.
diff --git a/submodules/externals/zrtpcpp b/submodules/externals/zrtpcpp
index 3cbbcf29f..93dbdb315 160000
--- a/submodules/externals/zrtpcpp
+++ b/submodules/externals/zrtpcpp
@@ -1 +1 @@
-Subproject commit 3cbbcf29f707adaaa00958c6e2c321e79a7b8e83
+Subproject commit 93dbdb3159f55bb35f69c13df1f60ac4901c88fb