1 files changed, 1 insertions, 1 deletions
diff --git a/build2/algorithm.ixx b/build2/algorithm.ixx
index 09d522f..84b0ee7 100644
--- a/build2/algorithm.ixx
+++ b/build2/algorithm.ixx
@@ -32,7 +32,7 @@ namespace build2
           const string& name,
           const string* ext,
           scope* scope,
-          const string* proj)
+          const optional<string>& proj)
   {
     return search (
       prerequisite_key {proj, {&type, &dir, &out, &name, ext}, scope});