diff --git a/doc/install_plasmapper.md b/doc/install_plasmapper.md
index 4c7b8dfa795cf1bd328dd2b0ccbda7b9fcc3e821..76133eaeac78eb040f88e48fa37a8141f30aa6fd 100755
--- a/doc/install_plasmapper.md
+++ b/doc/install_plasmapper.md
@@ -1,6 +1,10 @@
 # Instructions to install plasMapper on your server 
 
-On the targeted server type the following commands in a terminal :
+An installation step of plasmapper requires that you have java installed on your server (command jar). If this is not the case yet, type the following command (for Ubuntu):
+```sh
+sudo apt install default-jdk
+```
+Then, to install plasmapper on your server, type the following commands in a terminal :
 ```sh
    # extract PlasMapper source code
    cd opts/