diff --git a/environments/drupal-7.sh b/environments/drupal-7.sh
index 04bda49..db77cd9 100644
--- a/environments/drupal-7.sh
+++ b/environments/drupal-7.sh
@@ -7,11 +7,6 @@ function drupal_ti_download_drupal() {
 }
 
 function drupal_ti_install_drupal() {
-	if [ ! -f install.php ]
-	then
-		return -1
-	fi
-
 	php -d sendmail_path=$(which true) ~/.composer/vendor/bin/drush.php --yes site-install "$DRUPAL_TI_INSTALL_PROFILE" --db-url="$DRUPAL_TI_DB_URL"
 	drush use $(pwd)#default
 }
diff --git a/environments/drupal-8.sh b/environments/drupal-8.sh
index 8fe0b9e..359e07f 100644
--- a/environments/drupal-8.sh
+++ b/environments/drupal-8.sh
@@ -9,10 +9,6 @@ function drupal_ti_download_drupal() {
 }
 
 function drupal_ti_install_drupal() {
-	if [ ! -f install.php ]
-	then
-		return -1
-	fi
 	php -d sendmail_path=$(which true) ~/.composer/vendor/bin/drush.php --yes -v site-install "$DRUPAL_TI_INSTALL_PROFILE" --db-url="$DRUPAL_TI_DB_URL"
 	drush use $(pwd)#default
 }
diff --git a/functions/drupal.sh b/functions/drupal.sh
index 3115228..f9009f6 100644
--- a/functions/drupal.sh
+++ b/functions/drupal.sh
@@ -3,9 +3,9 @@
 # Common functionality for common tasks.
 
 #
-# Ensures that the right Drupal version exists.
+# Ensures that the right Drupal version is downloaded.
 #
-function drupal_ti_ensure_drupal() {
+function drupal_ti_ensure_drupal_download() {
 	# This function is re-entrant.
 	if [ -d "$DRUPAL_TI_DRUPAL_DIR" ]
 	then
@@ -30,16 +30,24 @@ function drupal_ti_ensure_drupal() {
 }
 
 #
-# Ensures that Drupal is installed.
+# Ensures that the right Drupal version is installed.
 #
-function drupal_ti_ensure_drupal_installed() {
-	drupal_ti_ensure_drupal
+function drupal_ti_ensure_drupal() {
+	# This function is re-entrant.
+	drupal_ti_ensure_drupal_download
+
+	# @todo Maybe use a different check for Drupal installed.
+	if [ -r "$TRAVIS_BUILD_DIR/../drupal_ti-drupal-installed" ]
+	then
+		return
+	fi
 
 	# Create database and install Drupal.
 	mysql -e "create database $DRUPAL_TI_DB"
 
-	cd drupal
+	cd "$DRUPAL_TI_DRUPAL_DIR"
 	drupal_ti_install_drupal
+	touch "$TRAVIS_BUILD_DIR/../drupal_ti-drupal-installed"
 }
 
 #
@@ -98,7 +106,7 @@ function drupal_ti_run_server() {
 		{ "$GOPATH/bin/hhvm-serve" -listen="$DRUPAL_TI_WEBSERVER_HOST:$DRUPAL_TI_WEBSERVER_PORT" 2>&1 | drupal_ti_log_output "webserver" ; } &
 	else
 		# start a web server on port 8080, run in the background; wait for initialization
-		{ drush runserver "$DRUPAL_TI_WEBSERVER_URL:$DRUPAL_TI_WEBSERVER_PORT" 2>&1 | drupal_ti_log_output "webserver" ; } &
+		{ php -S "$DRUPAL_TI_WEBSERVER_HOST:$DRUPAL_TI_WEBSERVER_PORT" 2>&1 | drupal_ti_log_output "webserver" ; } &
 	fi
 
 	# Wait until drush server has been started.
diff --git a/runners/behat/before_script.sh b/runners/behat/before_script.sh
index 7afe134..cebdd15 100755
--- a/runners/behat/before_script.sh
+++ b/runners/behat/before_script.sh
@@ -4,7 +4,7 @@
 set -e $DRUPAL_TI_DEBUG
 
 # Ensure the right Drupal version is installed.
-drupal_ti_ensure_drupal_installed
+drupal_ti_ensure_drupal
 
 # Ensure the module is linked into the code base and enabled.
 drupal_ti_ensure_module
diff --git a/runners/phpunit-core/before_script.sh b/runners/phpunit-core/before_script.sh
index d61d072..c19f3af 100755
--- a/runners/phpunit-core/before_script.sh
+++ b/runners/phpunit-core/before_script.sh
@@ -4,10 +4,7 @@
 set -e $DRUPAL_TI_DEBUG
 
 # Ensure the right Drupal version is downloaded.
-drupal_ti_ensure_drupal
-
-# Change directory to Drupal core directory.
-cd drupal
+drupal_ti_ensure_drupal_download
 
 # Ensure the module is linked into the code base.
 drupal_ti_ensure_module_linked
diff --git a/runners/simpletest/before_script.sh b/runners/simpletest/before_script.sh
index 1876359..5a526b6 100755
--- a/runners/simpletest/before_script.sh
+++ b/runners/simpletest/before_script.sh
@@ -4,7 +4,7 @@
 set -e $DRUPAL_TI_DEBUG
 
 # Ensure the right Drupal version is installed.
-drupal_ti_ensure_drupal_installed
+drupal_ti_ensure_drupal
 
 # Enable simpletest module.
 cd "$DRUPAL_TI_DRUPAL_DIR"