diff --git a/cmake/Modules/Packages/MACHDYN.cmake b/cmake/Modules/Packages/MACHDYN.cmake
index efe8a562eb..fab532541e 100644
--- a/cmake/Modules/Packages/MACHDYN.cmake
+++ b/cmake/Modules/Packages/MACHDYN.cmake
@@ -7,8 +7,8 @@ endif()
 option(DOWNLOAD_EIGEN3 "Download Eigen3 instead of using an already installed one)" ${DOWNLOAD_EIGEN3_DEFAULT})
 if(DOWNLOAD_EIGEN3)
   message(STATUS "Eigen3 download requested - we will build our own")
-  set(EIGEN3_URL "https://gitlab.com/libeigen/eigen/-/archive/3.3.7/eigen-3.3.7.tar.gz" CACHE STRING "URL for Eigen3 tarball")
-  set(EIGEN3_MD5 "9e30f67e8531477de4117506fe44669b" CACHE STRING "MD5 checksum of Eigen3 tarball")
+  set(EIGEN3_URL "https://gitlab.com/libeigen/eigen/-/archive/3.3.9/eigen-3.3.9.tar.gz" CACHE STRING "URL for Eigen3 tarball")
+  set(EIGEN3_MD5 "609286804b0f79be622ccf7f9ff2b660" CACHE STRING "MD5 checksum of Eigen3 tarball")
   mark_as_advanced(EIGEN3_URL)
   mark_as_advanced(EIGEN3_MD5)
   include(ExternalProject)
diff --git a/lib/machdyn/Install.py b/lib/machdyn/Install.py
index 16dd3038a8..2e90c9ca0f 100644
--- a/lib/machdyn/Install.py
+++ b/lib/machdyn/Install.py
@@ -17,11 +17,12 @@ parser = ArgumentParser(prog='Install.py',
 
 # settings
 
-version = '3.3.7'
+version = '3.3.9'
 tarball = "eigen.tar.gz"
 
 # known checksums for different Eigen versions. used to validate the download.
 checksums = { \
+              '3.3.9' : '609286804b0f79be622ccf7f9ff2b660', \
               '3.3.7' : '9e30f67e8531477de4117506fe44669b' \
 }
 
diff --git a/lib/machdyn/Makefile.lammps b/lib/machdyn/Makefile.lammps
index 6c914708dd..71db4fd4bc 100644
--- a/lib/machdyn/Makefile.lammps
+++ b/lib/machdyn/Makefile.lammps
@@ -1,5 +1,5 @@
 # Settings that the LAMMPS build will import when this package library is used
 
-machdyn_SYSINC = -I../../lib/includelink/eigen3
-machdyn_SYSLIB = 
-machdyn_SYSPATH = 
+machdyn_SYSINC =
+machdyn_SYSLIB =
+machdyn_SYSPATH =