diff --git a/ognibuild/resolver/__init__.py b/ognibuild/resolver/__init__.py
index 6dc48cc..bd72c51 100644
--- a/ognibuild/resolver/__init__.py
+++ b/ognibuild/resolver/__init__.py
@@ -27,6 +27,9 @@ class Resolver(object):
     def install(self, requirements):
         raise NotImplementedError(self.install)
 
+    def resolve(self, requirement):
+        raise NotImplementedError(self.resolve)
+
     def explain(self, requirements):
         raise NotImplementedError(self.explain)