diff --git a/scripts/_common.sh b/scripts/_common.sh
new file mode 100644
index 0000000..fe755ba
--- /dev/null
+++ b/scripts/_common.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# =============================================================================
+# COMPOSER
+# =============================================================================
+
+# Execute a composer command from a given directory
+# usage: composer_exec workdir COMMAND [ARG ...]
+exec_composer() {
+  local workdir=$1
+  shift 1
+
+  COMPOSER_HOME="${workdir}/.composer" \
+    php "${workdir}/composer.phar" $@ \
+      -d "${workdir}" --quiet --no-interaction
+}
+
+# Install and initialize Composer in the given directory
+# usage: init_composer destdir
+init_composer() {
+  local destdir=$1
+
+  # install composer
+  curl -sS https://getcomposer.org/installer \
+    | COMPOSER_HOME="${destdir}/.composer" \
+        php -- --quiet --install-dir="$destdir" \
+    || ynh_die "Unable to install Composer"
+
+  # update dependencies to create composer.lock
+  exec_composer "$destdir" install --no-dev \
+    || ynh_die "Unable to update Roundcube core dependencies"
+}
diff --git a/scripts/install b/scripts/install
index 8a0c07b..9fda0c2 100644
--- a/scripts/install
+++ b/scripts/install
@@ -6,7 +6,7 @@
 # IMPORT GENERIC HELPERS
 #=================================================
 
-# source _common.sh
+source _common.sh
 source /usr/share/yunohost/helpers
 
 #=================================================
@@ -114,6 +114,16 @@ cp ../conf/config.inc.php $final_path
 # Recalculate and store the config file checksum into the app settings
 ynh_store_file_checksum "$final_path/config.inc.php"
 
+#=================================================
+# INSTALL DEPENDENCIES
+#=================================================
+
+# Install composer
+init_composer "$final_path"
+
+# Install dependencies
+exec_composer "$final_path" update --no-dev
+
 #=================================================
 # GENERIC FINALIZATION
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index 5692f63..3bd8553 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -6,7 +6,7 @@
 # IMPORT GENERIC HELPERS
 #=================================================
 
-# source _common.sh
+source _common.sh
 source /usr/share/yunohost/helpers
 
 #=================================================
@@ -130,6 +130,16 @@ cp ../conf/config.inc.php $final_path
 # Recalculate and store the config file checksum into the app settings
 ynh_store_file_checksum "$final_path/config.inc.php"
 
+#=================================================
+# INSTALL DEPENDENCIES
+#=================================================
+
+# Install composer
+init_composer "$final_path"
+
+# Install dependencies
+exec_composer "$final_path" update --no-dev
+
 #=================================================
 # GENERIC FINALIZATION
 #=================================================