1 files changed, 6 insertions, 0 deletions
diff --git a/build/rule.cxx b/build/rule.cxx
index 03c86c8..f53d9d9 100644
--- a/build/rule.cxx
+++ b/build/rule.cxx
@@ -133,6 +133,8 @@ namespace build
     return target_state::unchanged;
   }
 
+  file_rule file_rule::instance;
+
   // alias_rule
   //
   match_result alias_rule::
@@ -148,6 +150,8 @@ namespace build
     return default_recipe;
   }
 
+  alias_rule alias_rule::instance;
+
   // fsdir_rule
   //
   match_result fsdir_rule::
@@ -238,4 +242,6 @@ namespace build
     default: return ts;
     }
   }
+
+  fsdir_rule fsdir_rule::instance;
 }