diff --git a/roundcubemail/Dockerfile b/roundcubemail/Dockerfile
index 5edf903..393f8c1 100644
--- a/roundcubemail/Dockerfile
+++ b/roundcubemail/Dockerfile
@@ -117,7 +117,7 @@ RUN set -ex; \
 	chown -R www-data:www-data /usr/src/roundcubemail/logs
 
 RUN set -ex; \
-	/usr/local/bin/composer \
+	/usr/local/bin/composer.phar \
         --working-dir=/usr/src/roundcubemail/ \
         --prefer-dist --prefer-stable \
         --no-update --no-interaction \
@@ -125,7 +125,7 @@ RUN set -ex; \
         require \
         	roundcube/carddav \
     ; \
-    /usr/local/bin/composer \
+    /usr/local/bin/composer.phar \
         --working-dir=/usr/src/roundcubemail/ \
         --prefer-dist --no-dev \
         --no-interaction \