diff --git a/ci/install_dart_latest.sh b/ci/install_dart_latest.sh
index b589f9b3..c4e40b4c 100755
--- a/ci/install_dart_latest.sh
+++ b/ci/install_dart_latest.sh
@@ -1,3 +1,5 @@
+set -e
+
 # Select Compiler
 if [ "$COMPILER" = "gcc" ]; then
 export CC=/usr/bin/gcc && export CXX=/usr/bin/g++
diff --git a/ci/install_magnum.sh b/ci/install_magnum.sh
index 9acb1b2d..3098b6fd 100755
--- a/ci/install_magnum.sh
+++ b/ci/install_magnum.sh
@@ -1,3 +1,5 @@
+set -e
+
 # Select Compiler
 if [ "$COMPILER" = "gcc" ]; then
 export CC=/usr/bin/gcc && export CXX=/usr/bin/g++
diff --git a/ci/install_packages.sh b/ci/install_packages.sh
index 450d39ea..275d1bfd 100755
--- a/ci/install_packages.sh
+++ b/ci/install_packages.sh
@@ -1,10 +1,14 @@
+set -e
+
 sudo apt-get -qq update
 sudo apt-get -y install software-properties-common mlocate
 sudo apt-add-repository -y ppa:dartsim/ppa
 sudo apt-get -qq update
 sudo apt-get install -y --no-install-recommends build-essential cmake pkg-config git libeigen3-dev libccd-dev libfcl-dev libboost-regex-dev libboost-system-dev libboost-filesystem-dev libboost-test-dev libbullet-dev libode-dev liboctomap-dev libtinyxml-dev libtinyxml2-dev liburdfdom-dev liburdfdom-headers-dev python3-pip python3-numpy libpython3-dev libxi-dev libxmu-dev freeglut3-dev libopenscenegraph-dev libassimp-dev libfmt-dev pybind11-dev
 
-sudo ln -s /usr/bin/python3 /usr/bin/python
+if [ ! -f /usr/bin/python ]; then
+    sudo ln -s /usr/bin/python3 /usr/bin/python
+fi
 
 if [ "$MAGNUM_GUI" = "ON" ]; then
     sudo apt-get install -y --no-install-recommends libopenal-dev libglfw3-dev libsdl2-dev libdevil-dev libpng-dev libfaad-dev libfreetype6-dev libglm-dev
diff --git a/scripts/install_osx.sh b/scripts/install_osx.sh
index c3a37c42..edadf97d 100755
--- a/scripts/install_osx.sh
+++ b/scripts/install_osx.sh
@@ -1,4 +1,4 @@
-set -x
+set -e
 
 CLEAN=0
 
diff --git a/scripts/install_ubuntu.sh b/scripts/install_ubuntu.sh
index fa247e5b..bda58b6a 100755
--- a/scripts/install_ubuntu.sh
+++ b/scripts/install_ubuntu.sh
@@ -1,3 +1,5 @@
+set -e
+
 CLEAN=0
 
 CLEAN=${1:-$CLEAN}