catkin_make error while following tutorial

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I'm new to ROS and was following this tutorial. In part 3, I get the following error when trying to execute catkin_make :

CMake Error at /opt/ros/kinetic/share/catkin/cmake/assert.cmake:17 (message):
Assertion failed: check for file existence, but filename
(RT_LIBRARY-NOTFOUND) unset.  Message: RT Library

Call Stack (most recent call first):
 /opt/ros/kinetic/share/catkin/cmake/tools/rt.cmake:42 (assert_file_exists)
 /opt/ros/kinetic/share/catkin/cmake/all.cmake:147 (include)
 /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:20 (include)
 CMakeLists.txt:52 (find_package)

This is the complete message log:

jan@jan:~/catkin_ws$ catkin_make
Base path: /home/jan/catkin_ws
Source space: /home/jan/catkin_ws/src
Build space: /home/jan/catkin_ws/build
Devel space: /home/jan/catkin_ws/devel
Install space: /home/jan/catkin_ws/install
####
#### Running command: "cmake /home/jan/catkin_ws/src -DCATKIN_DEVEL_PREFIX=/home/jan/catkin_ws/devel        -DCMAKE_INSTALL_PREFIX=/home/jan/catkin_ws/install -G Unix Makefiles" in "/home/jan/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /home/jan/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /opt/ros/kinetic
-- This workspace overlays: /opt/ros/kinetic
-- Using PYTHON_EXECUTABLE: /home/jan/anaconda3/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/jan/catkin_ws/build/test_results
-- Found gtest sources under '/usr/src/gtest': gtests will be built
-- Using Python nosetests: /home/jan/anaconda3/bin/nosetests
CMake Error at /opt/ros/kinetic/share/catkin/cmake/assert.cmake:17 (message):


Assertion failed: check for file existence, but filename
(RT_LIBRARY-NOTFOUND) unset.  Message: RT Library

Call Stack (most recent call first):
  /opt/ros/kinetic/share/catkin/cmake/tools/rt.cmake:42 (assert_file_exists)
  /opt/ros/kinetic/share/catkin/cmake/all.cmake:147 (include)
  /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:20 (include)
  CMakeLists.txt:52 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/jan/catkin_ws/build/CMakeFiles/CMakeOutput.log".
See also "/home/jan/catkin_ws/build/CMakeFiles/CMakeError.log".
Invoking "cmake" failed

Any help is appreciated.