diff --git a/client-qt6/Dockerfile b/client-qt6/Dockerfile
index 0d20924..0cb33ff 100644
--- a/client-qt6/Dockerfile
+++ b/client-qt6/Dockerfile
@@ -64,6 +64,7 @@ RUN \
         libkf6archive-dev \
         extra-cmake-modules \
         qtkeychain-qt6-dev \
+        libkdsingleapplication-qt6-dev \
         libsqlite3-dev \
         qt6-5compat-dev \
 # For cmocka based csync tests