diff --git a/build.sh b/build.sh
index 58ec096..999de19 100755
--- a/build.sh
+++ b/build.sh
@@ -93,11 +93,28 @@ install_packages () {
 		chmod +x $ECLIPSE_BIN_PATH
 	fi
 
+	set -o pipefail
 	$ECLIPSE_BIN_PATH -nosplash \
 			-application org.eclipse.equinox.p2.director \
 			-repository "$1" \
 			-installIU "$(parse_package_list $2)" \
 	| grep -v 'DEBUG'
+	set +o pipefail
+}
+
+# Uninstalls a given list of packages.
+uninstall_packages () {
+	if [[ "$OS" = "macos" ]]; then
+		chmod +x $ECLIPSE_BIN_PATH
+	fi
+
+	set -o pipefail
+	$ECLIPSE_BIN_PATH -nosplash \
+			-application org.eclipse.equinox.p2.director \
+			-repository "$1" \
+			-uninstallIU "$(parse_package_list $2)" \
+	| grep -v 'DEBUG'
+	set +o pipefail
 }
 
 # Displays the given input including "=> " on the console.
@@ -260,6 +277,13 @@ for p in ${ORDER[@]}; do
 		log "Skipping plug-in: $p."
 		continue
 	fi
+
+	# Check if Xtext (old version) must be uninstalled first.
+	if [[ "$p" = "xtext" ]]; then
+		log "Uninstalling plug-in: $p."
+		uninstall_packages "$UPDATESITES" "./packages/$p-uninstall-packages.list"
+	fi
+
 	log "Installing plug-in: $p."
 	install_packages "$UPDATESITES" "./packages/$p-packages.list"
 done
diff --git a/packages/xtext-uninstall-packages.list b/packages/xtext-uninstall-packages.list
new file mode 100644
index 0000000..190205e
--- /dev/null
+++ b/packages/xtext-uninstall-packages.list
@@ -0,0 +1,21 @@
+org.eclipse.xtend.sdk.feature.group
+org.eclipse.xtext.docs.feature.group
+org.eclipse.xtext.examples.feature.group
+org.eclipse.xtext.redist.feature.group
+org.eclipse.xtext.runtime.feature.group
+org.eclipse.xtext.sdk.feature.group
+org.eclipse.xtext.ui.feature.group
+org.eclipse.xtext.xbase.feature.group
+org.eclipse.xtext.xtext.ui.feature.group
+org.eclipse.xtext.xtext.ui.graph.feature.group
+org.eclipse.xtext.docs.feature.group
+org.eclipse.xtext.examples.feature.group
+org.eclipse.xtext.redist.feature.group
+org.eclipse.xtext.runtime.feature.group
+org.eclipse.xtext.sdk.feature.group
+org.eclipse.xtext.ui.feature.group
+org.eclipse.xtext.xbase.feature.group
+org.eclipse.xtext.xbase.lib.feature.group
+org.eclipse.xtext.xtext.ui.feature.group
+org.eclipse.emf.mwe2.language.ui
+org.eclipse.emf.mwe2.language.sdk.feature.group