diff --git a/CMakeLists.txt b/CMakeLists.txt
index a7ce4eb..b976fbf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 # OpenMM XTB Plugin
 #----------------------------------------------------
 
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.7.1)
 
 # We need to know where OpenMM is installed so we can access the headers and libraries.
 SET(OPENMM_DIR "/usr/local/openmm" CACHE PATH "Where OpenMM is installed")
@@ -10,12 +10,13 @@ INCLUDE_DIRECTORIES("${OPENMM_DIR}/include")
 LINK_DIRECTORIES("${OPENMM_DIR}/lib" "${OPENMM_DIR}/lib/plugins")
 
 # We also need to know where XTB is installed.
-FIND_LIBRARY(XTB_LIBRARY_PATH xtb)
 FIND_FILE(XTB_HEADER_PATH xtb.h)
-CMAKE_PATH(GET XTB_LIBRARY_PATH PARENT_PATH XTB_LIBRARY_DIR)
-CMAKE_PATH(GET XTB_HEADER_PATH PARENT_PATH XTB_INCLUDE_DIR)
-INCLUDE_DIRECTORIES("${XTB_INCLUDE_DIR}")
-LINK_DIRECTORIES("${XTB_LIBRARY_DIR}")
+CMAKE_PATH(GET XTB_HEADER_PATH PARENT_PATH XTB_INCLUDE_DIR_DEFAULT)
+SET(XTB_INCLUDE_DIR CACHE PATH XTB_INCLUDE_DIR_DEFAULT)
+
+FIND_LIBRARY(XTB_LIBRARY_PATH xtb)
+CMAKE_PATH(GET XTB_LIBRARY_PATH PARENT_PATH XTB_LIBRARY_DIR_DEFAULT)
+SET(XTB_LIBRARY_DIR CACHE PATH XTB_LIBRARY_DIR_DEFAULT)
 
 # Specify the C++ version we are building for.
 SET (CMAKE_CXX_STANDARD 11)