diff --git a/.travis.yml b/.travis.yml
index 860cf42..29de3c5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,6 @@
 
 language: cpp
+dist: bionic
 
 os:
   - linux
@@ -27,7 +28,7 @@ before_install:
 
 script:
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then
-    (bash scripts/setup_ubuntu_16.04.sh && cd linux_x86_64_release && make -j2 && make test);
+    (bash scripts/setup_ubuntu_18.sh && cd linux_x86_64_release && make -j2 && make test);
     fi
   - if [ "$TRAVIS_OS_NAME" == "osx" ]; then
     (bash scripts/setup_osx_anaconda.sh && cd osx_release && make -j2 && make test);
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 69d964b..342956d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ PROJECT (SYMDIFF CXX)
 OPTION(TCLMAIN      "Build with TCL Interpreter" ON)
 OPTION(PYTHON3      "Build Python 3 Interpreter" ON)
 
-set (CMAKE_CXX_STANDARD 17)
+set (CMAKE_CXX_STANDARD 14)
 
 SET (SUBDIRS
     src
diff --git a/scripts/setup_ubuntu_16.04.sh b/scripts/setup_ubuntu_18.sh
similarity index 84%
rename from scripts/setup_ubuntu_16.04.sh
rename to scripts/setup_ubuntu_18.sh
index 3731deb..2bdbd97 100644
--- a/scripts/setup_ubuntu_16.04.sh
+++ b/scripts/setup_ubuntu_18.sh
@@ -3,12 +3,12 @@
 CMAKE="/usr/bin/cmake"
 CMAKE_CXX_FLAGS=""
 CXX="/usr/bin/g++"
-TCL_ARCHIVE="/usr/lib/x86_64-linux-gnu/libtclstub.a"
-TCL_INCLUDE="/usr/include/tcl"
-TCL_BIN="/usr/bin/tclsh"
-PYTHON3_ARCHIVE="/usr/lib/x86_64-linux-gnu/libpython3.5m.so"
-PYTHON3_INCLUDE="/usr/include/python3.5m"
-PYTHON3_BIN="/usr/bin/python3.5m"
+TCL_ARCHIVE="/usr/lib/x86_64-linux-gnu/libtclstub8.5.a"
+TCL_INCLUDE="/usr/include/tcl8.5"
+TCL_BIN="/usr/bin/tclsh8.5"
+PYTHON3_ARCHIVE="/usr/lib/x86_64-linux-gnu/libpython3.6m.so"
+PYTHON3_INCLUDE="/usr/include/python3.6m"
+PYTHON3_BIN="/usr/bin/python3.6m"
 for TYPE in debug release; do
 ARCH=`uname -m`
 #  for ARCH in i386 x86_64; do
diff --git a/src/engine/Utility.cc b/src/engine/Utility.cc
index ab2fbac..0583919 100644
--- a/src/engine/Utility.cc
+++ b/src/engine/Utility.cc
@@ -18,6 +18,7 @@ limitations under the License.
 #include "EquationObject.hh"
 
 #include <algorithm>
+#include <functional>
 
 namespace Eqo {
 namespace {