diff --git a/tools/sdbus++-gen-meson b/tools/sdbus++-gen-meson
index 2de2032..665c50e 100755
--- a/tools/sdbus++-gen-meson
+++ b/tools/sdbus++-gen-meson
@@ -230,7 +230,7 @@
     # Determine the source files based on the YAMLs present.
     sources=""
     for s in ${interfaces[$1]}; do
-        sources="'${yamldir}/$1.${s}', "
+        sources="${sources}'${yamldir}/$1.${s}', "
     done
 
     # Create the target to generate the interface.md file.