diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e5d6260d..76b458d26 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -593,8 +593,8 @@ if(NOT ARMADILLO_FOUND)
           endif(${LINUX_DISTRIBUTION} MATCHES "Fedora" OR ${LINUX_DISTRIBUTION} MATCHES "Red Hat")
           message(FATAL_ERROR "The patch command is required to download and build armadillo")
      endif(NOT PATCH_EXECUTABLE)
-     set(armadillo_RELEASE 4.320.2)  
-     set(armadillo_MD5 "9c25eccbd850f06fd0428b2a2a6d645b") 
+     set(armadillo_RELEASE 4.400.0)  
+     set(armadillo_MD5 "616744dbc96af1c5d6d32c6c69f6fe94") 
      if(EXISTS ${CMAKE_CURRENT_BINARY_DIR}/download/armadillo-${armadillo_RELEASE}/armadillo-${armadillo_RELEASE}.tar.gz)
          set(ARMADILLO_PATCH_FILE ${CMAKE_CURRENT_BINARY_DIR}/armadillo-${armadillo_RELEASE}/armadillo_no.patch)
          file(WRITE ${ARMADILLO_PATCH_FILE} "")
diff --git a/README.md b/README.md
index 653bbbcbb..35286495d 100644
--- a/README.md
+++ b/README.md
@@ -72,9 +72,9 @@ $ sudo apt-get install libopenblas-dev liblapack-dev gfortran   # For Debian/Ubu
 $ sudo yum install lapack-devel blas-devel gcc-fortran          # For Fedora/CentOS/RHEL
 $ sudo zypper install lapack-devel blas-devel gcc-fortran       # For OpenSUSE
 
-$ wget http://sourceforge.net/projects/arma/files/armadillo-4.320.0.tar.gz
-$ tar xvfz armadillo-4.320.0.tar.gz
-$ cd armadillo-4.320.0
+$ wget http://sourceforge.net/projects/arma/files/armadillo-4.400.0.tar.gz
+$ tar xvfz armadillo-4.400.0.tar.gz
+$ cd armadillo-4.400.0
 $ cmake .
 $ make
 $ sudo make install