diff --git a/tools/sdbus++-gen-meson b/tools/sdbus++-gen-meson
index 1807108..5b61382 100755
--- a/tools/sdbus++-gen-meson
+++ b/tools/sdbus++-gen-meson
@@ -36,7 +36,7 @@
 ## if a repository contains old copies of the generated meson.build files and
 ## needs an update.  We should increment the version number whenever the
 ## resulting meson.build would change.
-tool_version="sdbus++-gen-meson version 8"
+tool_version="sdbus++-gen-meson version 9"
 function show_version() {
     echo "${tool_version}"
 }
@@ -180,7 +180,7 @@
     sources=""
     outputs=""
     for s in ${interfaces[$1]}; do
-        sources="'${yamldir}/$1.${s}', "
+        sources="${sources}'${yamldir}/$1.${s}', "
 
         case "${s}" in
             errors.yaml)