diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index a8daef67b..3872fd0e9 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -58,7 +58,7 @@ For Ubuntu, run the following commands:
 .. code-block:: bash
 
   sudo apt-get update
-  sudo apt-get install -y cmake pkg-config build-essential autoconf curl libtool unzip flex bison python # we install python here because python2 is required to build the webui
+  sudo apt-get install -y cmake pkg-config build-essential autoconf curl libtool unzip flex bison psmisc python # we install python here because python2 is required to build the webui
 
   # If you are not using Anaconda, you need the following.
   sudo apt-get install python-dev  # For Python 2.
diff --git a/java/doc/installation.rst b/java/doc/installation.rst
index 6adee9841..41189c0ae 100644
--- a/java/doc/installation.rst
+++ b/java/doc/installation.rst
@@ -17,7 +17,7 @@ For Ubuntu users, run the following commands:
 ::
 
   sudo apt-get update
-  sudo apt-get install -y maven cmake pkg-config build-essential autoconf curl libtool unzip flex bison python # we install python here because python2 is required to build the webui
+  sudo apt-get install -y maven cmake pkg-config build-essential autoconf curl libtool unzip flex bison psmisc python # we install python here because python2 is required to build the webui
 
   # If you are not using Anaconda, you need the following.
   sudo apt-get install python-dev  # For Python 2.
@@ -58,4 +58,4 @@ Run tests
 
   # in `ray/java` directory
   export RAY_CONFIG=ray.config.ini
-  mvn test
\ No newline at end of file
+  mvn test