1 files changed, 11 insertions, 0 deletions
diff --git a/build/variable.ixx b/build/variable.ixx
index 2d52d9f..c0059c5 100644
--- a/build/variable.ixx
+++ b/build/variable.ixx
@@ -37,6 +37,17 @@ namespace build
   }
 
   inline const value_proxy& value_proxy::
+  operator+= (std::string v) const
+  {
+    if (*p == nullptr)
+      *this = v;
+    else
+      as<list_value&> ().emplace_back (std::move (v));
+
+    return *this;
+  }
+
+  inline const value_proxy& value_proxy::
   operator= (dir_path v) const
   {
     p->reset (new list_value (std::move (v)));